A Portable Satellite Station Part 4 – 2.0 Station First Contacts!


Station Packed and Ready for Transport

Station Packed and Ready for Transport

With our new 2.0 Satellite station built, tested, and packed; we were ready to try it in a portable environment. Fortunately, the Nashua Area Radio Club had a Technician License class coming up and we thought that the new station test would be a great way for our students to learn about Amateur Radio Satellites.

Satellite Status from AMSAT Website

Satellite Status from AMSAT Website

Final preparations included checking the operational status of potential satellites on the AMSAT website. The page shown above is like a spotting cluster for LEO Satellites – it shows satellite activity as reported by HAM satellite operators. Using this information, we configured MacDoppler to track the active satellites.

Satellite Pass Predictions

Satellite Pass Predictions

Next, we used MacDoppler to generate pass predicts for the weekend of our Technical Class. We assembled this data for all of the potential satellites and color-coded the available passes to identify those which had the best chance of producing contacts.

With this done, we loaded our portable tower, antennas, and all of the rest of the gear into our pickup truck and transported it to the class site.

Sateliite Antennas Setup Portable

Satellite Antennas Setup Portable

The first step at the class site was to unload all of our gear and move the portable tower to a suitable location. We used a compass to orient the tower to true north and leveled it. We used the weight bags that we made up to anchor the tower securely and then installed the antennas, rotator loops, and control cables. The antenna system worked out very well in the portable environment and was easy to set up.

Satellite Antenna Details

Satellite Antenna Details

Here’s a closer to look at the LMR-400 UF coax cables which connect the antennas to the rest of the system. The loops just behind the antennas are necessary to keep the coax from effecting the pattern of the antennas. The coax cables shown were made long enough to allow the antennas to be rotated through their full travel in the azimuth and elevation directions without binding.

Satellite Station Portable - Radio and Supporting Equipment

Satellite Station Portable – Radio and Supporting Equipment

The final step in the portable setup was to put the IC-9100 Transceiver and Supporting Equipment together in the building and check everything out. As soon as we got everything hooked up and working, we heard an ON4 station through FO-29 which was near the end of a low angle pass. A very good sign!

We took some time to fine tune the calibration of our rotators and to check the operation of the computer controls – everything checked out fine. The video above shows MacDoppler controlling the Azimuth/Elevation rotator and the IC-9100 Transceiver during the testing.

First Contact using New 2.0 Station (AO-85)

First Contact using New 2.0 Station (via AO-85)

With all the setup done, it was time to try to make our first contact. Fortunately, we did not have long to wait. We caught a medium angle pass of AO-85, a U/V Mode FM Easy Sat. With MacDoppler setup and tacking, we immediately heard contacts being made through AO-85. I gave a whistle and adjusted my uplink VFO until I heard my signal coming back through AO-85. I gave a quick CQ call and immediately got a response from Jonathan, NS4L in Virginia, USA! It took on a few seconds to exchange call signs and grid squares and our first contract with our new station was in the log.

Explaining Satellite System to License Class

Explaining Satellite System to License Class

Our Technician License Class students were very interested in the station. We spent some time explaining the setup and demonstrating how it worked. We made more contacts between our class sessions using AO-85 and FO-29 (a V/U Mode Linear Transponder Satellite). Our most interesting contact was with Burt, FG8OJ in Guadeloupe through FO-29. It was great to work DX using the new station during the first time we used it.

We learned several things during our first use of the new station. First, while the 35 ft. maximum separation allowed between the antenna system and the rest of the station is adequate in many applications, the antenna system’s close proximity to the building we were in blocked passes to the west of us with this separation. We are going make up a second set of feed lines using a pair of 100 ft. long 7/8″ hardline coax cables to allow for a greater separation in portable deployments such as this one.

We were glad that we had the Heil Pro 7 Headset with us and we used it for most of our contacts. The separate speaker allowed our students to hear the contacts well and the boom microphone on the Pro 7 Headset eliminated feedback due to our own voice coming back through the satellites. We improvised a mono to stereo converter cable to connect the Heil Pro 7 Headset to one of the two speaker outputs on the IC-9100 Transceiver. This allowed the radio to drive the separate speaker and the headphones at the same time.

We were glad to have the low-noise preamps available. These were especially useful during low-angle satellite passes and the sequencing setup that we built worked well.

All in all, our first test of our new 2.0 Portable Satellite station was a success. Our license classes students enjoyed learning about Amateur Satellites and had fun along with us making contacts through a few of them. Our next goal will be to get packet modes and APRS working with our setup. We plan to do another article in this series when this part of our project is completed. Other articles in this series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Fred, AB1OC

A Portable Satellite Station Part 3 – 2.0 Station Radio and Supporting Equipment


Satellite Station Transceiver and Related Equipment

Satellite Station Transceiver and Related Equipment

With the Antenna System for our 2.0 Portable Satellite Station complete, we turned our attention to assembling the Transceiver and supporting equipment. The equipment used for this part of the project includes:

The Icom IC-9100 provides 100W on 2M and 75W on 70 cm which is more than enough power for our application. It also has some nice satellite features such as support for synchronized VFO tracking between the 2M and 70 cm VFOs in the radio. This radio also uses a single USB connection to allow computer control of the radio and creation of a sound card interface on the host computer. A Heil Pro 7 Headset will be used for operator audio to avoid feedback due to our audio coming back from the satellite. The Icom SP-23 speaker is included to allow observers to hear satellite contacts while they are in progress.

Radio Management via MacDoppler

Radio Management via MacDoppler

The MacDoppler software provides automated control of the IC-9100 including mode selection and automatic correction of both VFOs for doppler shift. These features greatly simplify the operation of the radio, especially when satellites with SSB/CW transponders are used.

The video above shows MacDoppler’s management of the IC-9100 Transceiver during a pass of AO-73. The constant adjustments of the VFOs takes care of doppler shift correction and ensure that our signal stays at a fixed position in the transponder passband of linear transponder satellites.

Preamp Sequencers and Output Monitoring

Preamp Sequencers and Output Monitoring

M2 Antenna Systems S3 Sequencers are used to provide control of the Advanced Receiver Research low-noise preamps on our portable tower. One of the nice features of the Icom IC-9100 is that it can be configured to provide separate keying lines for the 2M and 70cm VFOs. This allows a preamp to remain enabled on the receive VFO while the other VFO is in transmit mode with its preamp shutdown by the sequencer. This arrangement is very useful during tuning when one needs to hear your own signal coming back from a satellite. A custom-made cable assembly was made to interconnect the S3 Sequencers with the ACC socket on the IC-9100, the Weatherpack connector on the tower preamp control cable, and DC power.

We used the excellent WaveNode WN-2 Wattmeter again in our portable satellite setup. This is a modular output monitoring system which has sensor for VHF/UHF use as well as voltage, signal quality and other monitoring functions.

DC power for the setup is provided via a Powerwerx SS-30DV Power Supply and a RigRunner 40007U distribution unit. We use this power supply in all of our portable setups. It is light weight, provides plenty of power for a 100W station and accessories, and is quiet from an RF perspective.

Equipment Packing and Protection

Equipment Packing and Protection

With the transceiver test of the station complete, we turned our attention to transporting the setup. Proper protection of the equipment during transport was provided via a large case from Pelican. We combined this with a roller bag and an inexpensive storage bin for documentation and accessories which are not very fragile. We also included our RigExpert antenna analyzer in the setup to make testing of the station during setup in a portable environment easier.

Station Packed and Ready for Transport

Station Packed and Ready for Transport

With all of the assembly and testing of the components of our 2.0 Portable Satellite Station complete, we packed up all the components. We used an inexpensive furniture dolly to allow us to roll the tower around to load and unload it.

We are ready to test our new station in a portable application. More on that in the final article in this series. Other articles in the series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Fred, AB1OC

A Portable Satellite Station Part 2 – 2.0 Station Goals and Antenna System


M2 Antenna Systems LEO Pack On Display at Dayton 2016

M2 Antenna Systems LEO Pack on Display at Dayton 2016

We came upon the M2 Antenna Systems booth while walking around the exhibit halls at Dayton last year. M2 had one of their LEO Pack satellite antenna systems on display there. This got us thinking about building a new, more capable version of our portable satellite station. The LEO Pack is a relatively lightweight circularly polarized antenna system for working satellites using the 2 m and 70 cm bands. It turns out that AMSAT members can purchase the LEO Pack at a discount. Starting with the LEO Pack in mind, I began to lay out some goals for a new, 2.0 Portable Satellite Station:

  • Be capable of working all active Amateur LEO Satellites including those using linear transponders and digital modes
  • Be portable and manageable enough to be setup in an hour or less
  • Be simple enough to operate so that HAMs who are new to satellites can make all types of satellite contacts with a relatively short learning curve
  • Be manageable to transport and store
  • Utilize computer controlled antenna tracking to aim the antennas
  • Utilize computer control to manage radio VFOs to compensate for doppler shift
  • Be easy to transport and store
Computer Controlled Satellite Station Via MacDoppler

Computer Controlled Satellite Station via MacDoppler Software

We decided to take a computer controlled approach for both antenna aiming and Transceiver VFO management to meet our goal of making the station simple to operate for new satellite operators. After some research on the available options, we choose MacDoppler from Dog Park Software Ltd. for this purpose. MacDoppler runs under Mac OS/X and works well on our MacBook Air laptop computer which is very portable. This program also has broad support for many different rotator and transceiver platforms and is very easy to understand and use. Finally, the program features high quality graphics which should make the station more interesting to folks with limited or no experience operating through Amateur Satellites.

With the satellite tracking software chosen, we made selections for the other major components in the 2.0 Portable Satellite Station as follows:

I will explain these choices in more detail as our article series proceeds.

Glen Martin Roof Tower

Glen Martin 4.5′ Roof Tower

Our solution to making the antenna system portable is built around a Glen Martin 4.5′ Roof Tower. This short tower is a high-quality piece made of extruded aluminum parts. The tower is very sturdy when assembled and is light in weight. We added a pair of extended “feet” to the tower which are fabricated from 36″ x 2″ x 1 /4″ strap steel. This gives the tower a firm base to sit on and allows us to use sandbags to weight it down (more on this later).

Our chosen Yaesu G-500 AZ/EL Rotator is a relatively inexpensive Azimuth/Elevation rotator which is suitable for light-weight satellite antennas such as those in the LEO Pack. This rotator can be installed as a single unit on the top of a tower or separated using a mast. We choose the latter approach as it is mechanically more robust and helps to keep the center of gravity for our portable antenna system low for improved stability.

Yaesu G-5500 Elevation Rotator

Yaesu G-5500 Elevation Rotator

Separating the Yaesu AZ/EL rotator requires as short mast and a thrust bearing to be used. The mast was made from an 1-3/4″ O.D. piece of EMT tubing from our local hardware store. The thrust bearing is a Yaesu GS-065 unit. Both of these pieces fit nicely in the Glen Martin Tower. The thrust bearing provides support for the LEO Pack and G-500 elevation rotator and greatly reduces stress on the azimuth rotator. We also added a Yaesu GA-300 Shock Absorber Mount to the azimuth rotator. This part provides shock isolation for and reduces strain on the azimuth rotator during the frequent starts and stops which occur during satellite tracking.

LMR-400 Feed-lines And Antenna Connection Jumpers

LMR-400UF Feed-lines and Antenna Connection Jumpers

We decided to use LMR-400 UltraFlex coax throughout our antenna system. LMR-400UF coax provides a good balance between size, flexibility and loss for our application. To keep feed-line losses reasonable, we choose to limit the total length of the coax from the transceiver output to the antenna feed point to 50′. This results in a loss of about 1.3 dB on the 70 cm band. The result is that our planned IC-9100 Transceiver which has a maximum output of 75W on 70 cm will deliver a little more than 50W maximum at the feed point of the 70 cm yagi. This should be more that enough power to meet our station goals. Allowing a total of 15′ for antenna rotator loops and transceiver connections, we settled upon 35′ for the length of our coax feed-lines between the tower and the station control point.

Portable Tower Cable Connections and Base Straps

Portable Tower Cable Connections and Base Straps

We added some custom fabricated plates to the tower to act as a bulkhead for feed line and control cable connections and to mount our low-noise preamplifiers. The control connections for the rotators and preamps were made using 6-pin Weatherpack connectors and rotator control cable from DXEngineering. The control cables are also 35′ long to match the length of our coax feed lines. This length should allow the tower and the control point to be separated by a reasonable distance in portable setups.

Low-Noise Preamplifiers From Advanced Receiver Research

Low-Noise Preamplifiers from Advanced Receiver Research

We added tower-mounted Low-Noise Preamplifiers from Advanced Receiver Research to improve the receive sensitivity and noise figure for our satellite antenna system. Two preamps are used – one each for the 2 m and one for 70 cm antennas. While these units can be RF switched, we decided to include the preamp control lead in our control cable to allow for control of the preamp switching via sequencers. This was done to provide an extra measure of protection for the preamps.

Levels And Compass For Tower Setup

Levels and Compass for Tower Setup

We added a compass and pair of bubble levels to the tower assembly to make it easier to orient and level it during setup. This picture above also shows the Yaesu shock absorbing mount for the azimuth rotator.

Weight Bags To Anchor Portable Tower

Weight Bags to Anchor Portable Tower

Finally, we added a set of weight bags to securely anchor the tower when it is set up in a portable environment. These bags are filled with crushed stone and fasten to the legs of the Glen Martin tower with velcro straps.

LEO Pack Antenna Parts

LEO Pack Antenna Parts

With the tower and rotator elements complete, we turned our attention to the assembly of the M2 LEO Pack. The LEO pack consists of two circularly polarized yagis for the 2m and 70 cm bands. The 2m Yagi is an M2 Systems 2MCP8A which has 8 elements (4 horizontal and 4 vertical) and provides 9.2 dBic of forward gain. The 70 cm Yagi is an M2 Systems 436CP16 with 16 elements (8 horizontal and 8 vertical) and provides 13.3 dBic of forward gain. Both Yagi’s are meant to be rear mounted on an 8.5′ aluminum cross boom which is included in the LEO Pack. The picture above shows all of the parts for the two antennas before assembly. It took us about a 1/2 day to assemble and test the antennas and both produced the specified SWR performance when assembled and test in clear surroundings.

Assembled LEO Pack On Portable Tower

Assembled LEO Pack on Portable Tower

The picture above shows the assembled LEO pack on the portable tower. We attached a short 28″ piece of mast material to the cross boom as a counterweight to provide better overall balance and to minimize strain on the elevation rotator. The antennas and the two outer sections of the mast can be easily removed to transport the antenna system.

2m Circularly Polarized Yagi Feed Point

2m Circularly Polarized Yagi Feed Point

The LEO Pack yagis achieve circular polarization via a matching network which drives the vertical and horizontal sections of the antennas with a 90 degree phase shift. The phase shift (and a final 50 ohm match) is achieved using 1/4 wave delay lines made of coax cables. We configured our antennas for right-hand circular polarization. The choice between right and left hand circular polarization is not a critical one in our LEO satellite application as most LEO satellites are not circularly polarized. The advantage of circular polarization in our application is the minimization of spin fading effects.

Green Heron RT-21 Az/El Rotator Controller

Green Heron RT-21 AZ/EL Rotator Controller

The final step in the construction of our antenna system was to add the rotator controller and test the computer aiming system. We have had very good results using Green Heron Engineering rotator controllers in our home station so we selected their RT-21 AZ/EL rotator controller for this application. The RT-21 AZ/EL rotator controller is really two rotator controllers in a single box. The rotator control parameters such as minimum and maximum rotator speed, ramp, offset, over travel and others can be independently set for each rotator.

Rotator Test Using MacDoppler

Rotator Test Using MacDoppler

The RT-21 AZ/EL Rotator Controller connects to our computer via a pair of USB cables. We run Green Heron’s GH Tracker software on our MacBook Air laptop to manage the computer side of the rotator controller and to provide a UDP protocol interface to the MacDoppler tracking software. The picture above shows the test setup used to verify the computer controlled antenna pointing system.

Mixed OS/X and Windows Software Environment

Mixed OS/X and Windows Software Environment

One challenge associated with selecting a Mac OS/X platform for computer control is what to do about the inevitable need to run Windows software as part of the system. In addition to the GH Tracker software, the WaveNode WN-2 Wattmeter and digital modem software for satellite/ISS APRS and other applications require a Windows run-time environment. To solve this problem, we use a virtual machine environment implemented using VMware Fusion and Windows 10 64-bit on our MacBook Air Laptop along with Mac OS/X. Using the Unity feature of VMware Fusion allows us to run windows apps such as GH Tracker as if they were native Mac OS/X apps. The picture above shows an example of this.

Rotator Controller and Software Configuration

Rotator Controller and Software Configuration

With the antennas removed from the cross boom, we tested the operation of the computer controlled tracking system. The Yaesu G-5500 AZ/EL Rotator have some limits as to its pointing accuracy and backlash performance.  Experimentation with the combination of  the RT-21 AZ/EL rotator controller, GH Tracker and MacDoppler setups was required to achieve smooth overall operation. We finally settled on a strategy of “lead the duck” tracking. The idea here is to set up the rotators so that they over-travel by a degree or so when the computer adjusts them and couple this with a relatively wide 2-3 degree tracking resolution. This maximizes the overall accuracy of the pointing system and minimizes the tendency towards constant start-stop operation of the rotators during satellite tracking. Our current configuration for all of the elements involved in the tracking system is shown above.

With the antenna system complete and tested, we can move onto the next step in our project – the construction of a computer controlled transceiver system. We will cover this element in the next part  in this series. Other articles in the series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Fred, AB1OC

A Portable Satellite Station Part 1 – A Simple Station for AO-85


Portable Satellite Station Contact

Portable Satellite Station Contact

Our club, the Nashua Area Radio Club, has quite a few members who are interested in space communications. We decided to build a simple portable satellite station last year for our 2016 Field Day operation to learn about satellite communications and to create something new for folks to work with during 2016 Field Day.

Simple Portable Satellite Station

Simple Portable Satellite Station

Our 1.0 Portable Satellite Station was a relatively simple setup built around an HT, an Elk 2m/70cm satellite antenna, and some gear to improve the receive performance and transmit power output of the HT. All of the gear was mounted on a board to make it easy to transport and it is powered from a LIPO rechargeable battery. The gear in our 1.0 station is made up of the following:

Improved Satellite Antenna Mount

Improved Satellite Antenna Support

Our first contacts with our 1.0 station were made using the Elk Antenna hand-held. Later, we created a “plumber’s special” setup with a camera tripod to make pointing the antenna easier. Note the angle meter from a local hardware store which measures the elevation angle of the antenna.

AO-85 (Fox-1A) U/V Mode FM Cube Sat

AO-85 (Fox-1A) U/V Mode FM Cube Satellite

This setup worked great for making FM contacts through AO-85 (Fox-1A), a  U/V mode FM EasySat. We used the 1.0 station on multiple occasions including Field Day 2016 and several of our club members used it to make their first satellite contacts. The Full-Duplex HT allowed us to hear our own signal coming back from the satellite which was an important tool to help with aiming the antenna properly. The ELK Dual-Band antenna is also a good choice because it uses a single feed point and a single polarization for both the 2m and 70cm bands.

1.0 Station Team Operating Approach

1.0 Station Team Operating Approach

We used the team operating approach outlined above. This worked especially well for new folks who had not made a satellite contact before as it enabled each of the three team members involved in making the contact to focus on a specific part of the contact. We used orange plastic tent stakes to make AOS, Time of Closest Approach, and EOS to mark headings for each satellite pass. Small flashlights used at the stakes made them glow for night-time passes.

We certainly had a lot of fun with our 1.0 Satellite Station and I expect that we’ll continue to use it. As we gained a little experience with AO-85, we decided that we wanted to build a more capable Portable Satellite Station which we could use to operate with linear transponder satellites and which included a tracking system and better antennas. I know from experience with our home satellite station that DX contacts are possible using higher altitude linear transponder satellites like FO-29.

We would also like to be able to use APRS and other digital modes through satellites as well as receive SSTV pictures from space.

These goals have become the basis for building our Portable Satellite Station 2.0. More on the new station in Part 2 of this series. Other articles in the series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

73,

Fred (AB1OC)

Fall Antenna Projects – A New Low-Band Receive Antenna System


NCC-1 Receive Antenna System Control Unit and Filters

NCC-1 Receive Antenna System Control Unit and Filters

Anita and I like to take advantage of the mild fall weather to do antenna projects at our QTH. We have completed two such projects this fall – the installation of a Two-Element Phased Receive System and a rebuild of the control cable interconnect system at the base of our tower.

NCC-1 Receive Antenna System Components

NCC-1 Receive Antenna System Components

Our first project was the installation of a DXEngineering NCC-1 Receive Antenna System. This system uses two receive-only active vertical antennas to create a steerable receive antenna system. The combination can work on any band from 160m up to 10m. We set ours up for operation on the 80m and 160m bands.

NCC-1 Receive System Antenna Pattern

NCC-1 Receive System Antenna Pattern

The NCC-1 System can be used to peak or null a specific incoming signal. It can also be applied to a noise source to null it out. The direction that it peaks or nulls in is determined by changing the phase relationship between the two Active Antenna Elements via the NCC-1 Controller.

NCC-1 Filter Installation

NCC-1 Filter Installation

The first step in the project was to open the NCC-1 Control Unit to install a set of 80m and 160m bandpass filter boards. These filters prevent strong out-of-band signals (such as local AM radio stations) from overloading the NCC-1. The internal switches were also set to configure the NCC-1 to provide power from an external source to the receive antenna elements through the connecting coax cables.

Installed Active Receive Antenna Element

Installed Active Receive Antenna Element

The next step in the project was to select a suitable location for installing the Receive Antenna Elements. We choose a spot on a ridge which allowed the two Antenna Elements to be separated by 135 ft (for operation on 160m/80m) and which provided a favorable orientation toward both Europe and Japan. The antenna elements use active circuitry to provide uniform phase performance between each element’s 8 1/2 foot whip antenna and the rest of the system. The antenna elements should be separated by a 1/2 wavelength or more on the lowest band of operation from any towers or transmit antennas to enable the best possible noise rejection performance.

Received Antenna Element Closeup

Received Antenna Element Closeup

The two Antenna Elements were assembled and installed on 5 ft rods which were driven into the ground. To ensure a good ground for the elements and to improve their sensitivity, we opted to install 4 radials on each antenna (the black wires coming from the bottom of the unit in the picture above). The Antenna Elements are powered through 75 ohm flooded coax cables which connect them to the NCC-1 Control Unit in our shack. The coax cable connections in our setup are quite long –  the longer of the pair being approximately 500 ft. The use of flooded coax cable allows the cables to be run underground or buried. Should the outer jacket become nicked, the flooding glue inside the cable will seal the damage and keep water out of the cable.

Receive RF Choke

Receive RF Choke

It is also important to isolate the connecting coax cables from picking up strong signals from nearby AM Radio stations, etc. To help with this, we installed Receive RF Chokes in each of the two coax cables which connect the Antenna Elements to the NCC-1. These chokes need to be installed on ground rods near the Antenna Elements for best performance.

Underground Cable Conduit In Our Yard

Underground Cable Conduit In Our Yard

We ran the coax cables underground inside cable conduits for a good portion of the run between the antenna elements and our shack. The conduits were installed in our yard when we built our tower a few years back so getting the coax cables to our shack was relatively easy.

Receive Antenna Coax Ground System

Receive Antenna Coax Ground System

The last step in the outdoor part of this project was to install a pair of 75 ohm coax surge protectors near the entry to our shack. An additional ground rod was driven for this purpose and was bonded to the rest of our station’s ground system. We routed both of the 75 ohm coax cables from the two Antenna Elements through surge protectors and into our shack. Alpha-Delta makes the copper ground rod bracket shown in the picture for mounting the surge protectors on the ground rod.

Antenna Equipment Shelf In Our Shack (The NCC-1 Control Unit Is At The Bottom)

Antenna Equipment Shelf In Our Shack (The NCC-1 Control Unit Is At The Bottom)

The installation work in our shack began with the construction of a larger shelf to hold all of our antenna control equipment and to make space for the NCC-1. The two incoming coax cables from the Antenna Elements were connected to the NCC-1.

microHAM Station Master Deluxe Antenna Controller

microHAM Station Master Deluxe Antenna Controller

Antenna switching and control in our station is handled by a microHAM System. Each radio has a dedicated microHAM Station Master Deluxe Antenna Controller which can be used to select separate transmit and receive antenna for the associated radio. The microHAM system allows our new Receive Antenna System to be shared between the 5 radios in our station.

Antenna Switching Matrix

Antenna Switching Matrix

The first step in integrating the Receive Antenna System was to connect the output of the NCC-1 to the Antenna Switching Matrix outside our shack. We added a low-noise pre-amp (shown in the upper left of the picture above) to increase the sensitivity of the Antenna System. The blue device in the picture is a 75 ohm to 50 ohm matching transformer which matches the NCC-1’s 75 ohm output to our 50 ohm radios. The other two pre-amps and transformers in the picture are part of our previously installed 8-Circle Receive Antenna System.

Multi-Radio Sequencer

Multi-Radio Sequencer

The Antenna Elements must be protected from overload and damage from strong nearly RF fields from our transmit antennas. In a single radio station, this can be handled via a simple sequencer unit associated with one’s radio. In a multi-op station such as ours, it is possible for a different radio than the one which is using the Receive Antenna System to be transmitting on a band which would damage the Receive Antenna System. To solve this problem, we built a multi-radio sequencer using one of the microHAM control boxes in our station. The 062 Relay Unit shown above has one relay associated with each of the five radios in our station. The power to the Receive Antenna System is routed through all 5 of these relays. When any radio transmits on a band that could damage the Antenna Elements, the associated relay is automatically opened 25 mS before the radio is allowed to key up which ensures that the system’s Antenna Elements are safely powered down and grounded.

NCC-1 Controls

NCC-1 Controls

So how well does the system work? To test it, we adjusted the NCC-1 to peak and then null a weak CW signal on 80m. This is done by first adjusting the Balance and Attenuator controls on the NCC-1 so that the incoming signal is heard at the same level by both Antenna Elements. Next, the B Phase switch is set to Rev to cause the system to operate in a signal null’ing configuration and the Phase control is adjusted to maximize the null’ing effect on the target signal. One can go back and forth a few times between the Balance and Phase controls to get the best possible null. Finally, the incoming signal is peaked by setting the B Phase switch to Norm.

Peaked And Null'ed CW Signal

Peaked And Null’ed CW Signal

The picture above shows the display of the target CW signal on the radio using the NCC-1 Antenna System. If you look closely at the lower display in the figure (null’ed signal) you can still see the faint CW trace on the pan adapter. The difference between the peak and the null is about 3 S-units or 18 dB.

NCC-1 Used For Noise Cancellation

NCC-1 Used For Noise Cancellation

The NCC-1 can also be used to reduce (null out) background noise. The picture above shows the result of doing this for an incoming SSB signal on 75m. The system display at the top shows an S5 SSB signal in the presence of S4 – S5 noise (the lower display in the picture). Note how clean the noise floor for the received SSB signal becomes when the unit is set to null the noise source which comes from a different direction than the received SSB signal.

We are very pleased with the performance of our new Receive Antenna System. It should make a great tool for DX’ing on the low-bands. It is a good complement to our 8-circle steerable receive system which we use for contesting on 160m and 80m.

Tower Control Cable Interconnects (Bottom Two Gray Boxes)

Tower Control Cable Interconnects (Bottom Two Gray Boxes)

Our other antenna project was a maintenance one. We have quite a number of control leads going to our tower. When we built our station, we placed surge protectors at the base of our tower and routed all of our control leads through exposed connections on these units. Over time, we found that surge protection was not necessary and we also became concerned about the effects that sunlight and weather were having on the exposed connections. To clean all of this up, we installed two DXEngineering Interconnect Enclosures on our tower and moved all the control cable connections inside them.

Inside View Of Interconnect Enclosures

Inside View Of Interconnect Enclosures

We began with a pair of enclosures from DXEngineering and we mounted screw terminal barrier strips on the aluminum mounting plates in each enclosure. The aluminum plates are grounded via copper strap material to our tower.

Closer Look At One Of The Interconnect Enclosures

Closer Look At One Of The Interconnect Enclosures

The picture above shows one of the interconnection boxes. This one is used to connect our two SteppIR DB36 Yagi Antennas and some of the supporting equipment. The barrier strips form a convenient set of test points for troubleshooting any problems with our equipment on the tower. There are almost 100 control leads passing through the two enclosures and this arrangement keeps everything organized and protected from the weather.

With all of our antenna projects complete, we are looking forward to a fun winter of contesting and low-band DX’ing.

73,

Fred, AB1OC

 

A New Project – Digital Fast Scan Amateur Television


Digital ATV CQ Call

Digital ATV CQ Call

Skip, K1NKR a local friend and VHF/UHF expert and I began talking about the idea of building a Fast Scan Amateur Television (ATV) System some time ago. Our early research and the antenna equipment which we had in place at our stations led us to plan our ATV project around the 70 cm band. The 70 cm band plan in the United States has allocations for Fast Scan ATV transmissions with a bandwidth of up to 6 MHz. Our research led us to Jim Andrews, KH6HTV’s excellent website where we discovered that it was possible to build a Digital ATV station using reasonably priced commercially available DVB-T format Modulators and Demodulators. Jim’s site has a wealth of great Applications Notes on Digital ATV and its a great place to start to learn about this technology. A combination of a DVB-T Modulator and Demodulator from Hi-Des was chosen as the heart of our Digital ATV System. We also worked with Jim to secure the needed Wideband Linear Power Amplifiers for the 70 cm band. We began receiving the equipment to build our Digital ATV Stations late last year. We’ve done quite a bit of testing on the air and some custom development work which has resulted in a pair of excellent performing Digital ATV stations. The picture above shows a Digital ATV “CQ” that I sent to initiate one of our early QSOs.

Digital ATV Transceiver

Digital ATV Transceiver

Here’s a picture of Skip receiving my “CQ” at his end. The picture quality produced by the equipment that we’re using and the DVB-T format is phenomenal. The Hi-Des Modulators which we are using have a large number of parameters which can be set to determine the format and bandwidth of the signals we generate. After some experimentation, we have settled on using QPSK modulation and a 6 MHz signal bandwidth. This combination delivers excellent picture quality with more that adequate motion performance. We see very few if any picture artifacts using our current format. We’ve also done some experimentation with QPSK and a 4 MHz signal bandwidth. I plan to share more on signal formats in a future article on our blog.

Digital ATV System User Interface

Digital ATV System User Interface

We are both using HD Digital Camcorders as our primary video signal sources and 1080p monitors to display our received signals. I opted to include an HDMI Video Switch from Gefen in my setup which also allows me to send video and graphics from a variety of different sources including my PC over the air. The monitor in the picture above on the right is a touch screen display which I use to control my ATV Transceiver system.

AB1OC Digital ATV Transceiver

AB1OC Digital ATV Transceiver

Early on, I decided to build a Transceiver like setup. I wanted to create a unit which was simple to use just like the HF Transceivers that are available today. Some of the key capabilities that I wanted to create included:

  • Real-time selection and switching between multiple HD video sources
  • Transmission of PC sourced Video and Graphics over the air
  • Preview and cueing of the next video transmission while receiving
  • Simultaneous display of both receive and pending transmit video
  • Built-in Transmit/Receive (T/R) switching with termination and protection of the Tx power stage
  • Sequencing of T/R stages including my tower mounted pre-amplifier system
  • Power and SWR monitoring with automatic trip on high SWR
  • An internal low-noise RF preamplifier to provide additional receive signal gain if needed
  • Touch screen graphical interface for configuration and operating the system
  • Recording of both sides of on-air video QSOs to an attached PC

To achieve these goals, I decided to build a Raspberry Pi 2 based Linux controller of my ATV Transceiver and to package all of the ATV components and video switching/conversion gear needed in a small rack mount enclosure. Many of the components in the system communicate with each other over an ethernet LAN and the transceiver is networked to computers and other devices via an external ethernet connection. More on the details of the Transceiver design to come in a future article.

Skip and I recently produced a short video to demonstrate how Fast Scan Digital ATV works and to show the quality that these systems are capable of producing. Our project is still a work in progress and I expect that we will continue to learn as we perform more tests and continue development of our systems. I plan to post additional articles here to share the details of our designs and learning from our on-air testing as we proceed.

– Fred (AB1OC)

Software Defined Radio/Remote Operating Gateway Part 2 – Client/Server Setup And Software


 

Remote Operating Gateway Client/Server Architecture

Remote Operating Gateway Client/Server Architecture

The next step in our Software Defined Radio/Remote Operating Project was to build a Remote Operating Gateway System in our shack and setup Client PCs to operate our station remotely. In a previous article, we explained how we integrated a FlexRadio 6700 Software Defined Radio (SDR) into our station to create a platform to build our remote operating project around. The project has turned out to be somewhat involved so we will be providing a series of articles to explain what we did:

In this article, we will explain the additional hardware and software that we used to enable remote operating as well as some additional equipment we added to our Client PCs that we use to operate our station remotely. The reader may want to refer to the picture above as you browse this article to better understand how the parts in our remote operating setup fit together. You can click on any of the pictures here on our blog to see a larger, easier to read version of them.

SmartSDR Software

SmartSDR Software Operating With A FlexRadio 6700 SDR

FlexRadio’s SmartSDR Software handles operating the SDR remotely. At the present state of maturity, SmartSDR can operate over a wired or wireless Ethernet LAN connection. At present, both SmartSDR and the FlexRadio-6xxx hardware must be on the same sub-network to function properly. FlexRadio has indicated that they plan to enable SmartSDR operation over wide-area broadband internet connections in the future. The design that we chose for our Remote Operating Gateway and Client PCs will allow operation of our entire station over the internet when SmartSDR is capable of fully supporting this. SmartSDR handles remoting of audio (microphone and speakers/headphones) as well as CW keying over our Home Network (more on this later) as well as control of the radio. With these key functions taken care of, we need to also remote the following functions of our station to fully support remote operation:

Remote control of equipment power is particularly important to provide a means to reset/restart equipment remotely as well as a means to shut down the Transmitter remotely.

Remote GW Control Stack - Antenna, Power and Monitoring

Remote Gateway Control Stack – Antenna, Power and Monitoring

Remote control of power for the components in our Remote Operating Setup is handled by a RIGRunner 4005i power control device. This unit provides remote power control over a network for up to 5 separate groups of devices. It also provides voltage/current monitoring and solid state over-current protection as well.

RIGRunner Remote Power Control Setup

RIGRunner Remote Power Control Setup

The figure above shows how we setup our RIGRunner 4005i. The device is controlled over our Home Network via a standard Web Browser. As you can see from the picture above, this devices lets us remotely control power to all of the devices in our Remote Operating Setup.

Remote Control Relay Unit

Remote Control Relay Unit

The FlexRadio-6700 SDR requires some additional power control handling. Simply removing and applying power to the FlexRadio-6700 SDR will reset the radio and leave it in a power off state. The FlexRadio-6700 SDR does have a remote power control input which can be controlled via a relay closure. We used a microbit Webswitch 1216H device to provide a remotely controlled relay closure to control the power off/on for the FlexRadio-6700 SDR.

Flex-6700 On/Off Control Via microbit Webswitch

Flex-6700 On/Off Control Via microbit Webswitch

The microbit Webswitch 1216H relay unit is also controlled over our Home Network via a standard Web Browser.

SmartSDR Setup - Tx Keying, Tx Interlock and Remote Power Control

SmartSDR Setup – Remote On/Off Control

The FlexRadio-6700 SDR is configured for remote on/off operation via the Radio Setup dialog in SmartSDR as shown above. A cable is run between the remote power on/off port on the FlexRadio-6700 SDR and the microbit Webswitch 1216H relay unit to complete this part of our Remote Control System.

Beams On Our Tower

Beams On Our Tower

It is also important to have full remote control of our Antennas and Rotators to effectively use our station from outside our shack. Control of our Rotators is accomplished by software which remotes serial COM ports over our Home Network.

Network Serial Port Kit

Network Serial Port Kit

We used the Fabulatech’s Network Serial Port Kit package to remote the serial COM ports used to control the microHAM Station Master Deluxe Antenna Controller, the associated antenna Rotators and the WinKeyer associated with our FlexRadio-6700 SDR. This software runs on both the local Server computer in our shack which hosts the Remote Operating Setup and any Client PCs which are used to operate our station remotely.

microHAM Station Master Deluxe Antenna Control via Teamviewer and Development App

microHAM Station Master Deluxe Development Application Via TeamViewer

There is not currently a production software tool to enable remote control of the microHAM Station Master Deluxe Antenna Controllers which we use in our shack. I am planning to develop our own application to do this in the future. The folks at microHAM have been so kind to provide me with the interface specifications needed to control the Station Master Deluxe Antenna Controller remotely along with a Developer Only test application (shown above) which can be used to understand the microHAM Device Protocol. In the interim, I have been using the microHAM Developer Only application along with the TeamViewer Remote Control Software to control antenna selection remotely and to monitor the position of the current selected rotators.

Shack Remote Operating Gateway Server PC Applications

Shack Remote Operating Gateway Server PC Applications

The remaining software required for remote control of our station is provided by the Elecraft applications which control the KPA500 Amplifier, KAT500 Auto-Tuner, and W2 Wattmeter which are used in our Remote Operating Gateway setup. All of these applications along with the microHAM Developer Only Application for Station Master Deluxe control and the DDUtil Program which interworks the FlexRadio-6700 SDR CAT interface with the Station Master Deluxe (see the previous article in this series) are shown above running on our Shack Server PC. This PC is on at all times and is protected by a Uninterruptible Power System (UPS) to ensure that it runs trouble-free.

Remote Operating PC Client Software Applications

Remote Operating PC Client Software Applications

In addition to FlexRadio SmartSDR, each of the Server Side PC applications has a corresponding Client Side application which is used on the Remote Operating Client PC. Shown above are the three Elecraft Client applications for Amplifier, Auto-Tuner and Wattmeter control and monitoring. The client side Network Serial Port Kit application which replicates the WinKeyer, microHAM Station Master Deluxe and Rotator Control COM ports is also shown.

Heil Microphone And USBQ Adapter

Heil Microphone And USBQ Adapter

The PC in our home office will be a primary remote operating location for our station. Audio quality is important to us and we wanted to ensure that the quality of our audio was just as good operating remotely as it is when we operate from our Shack. To accomplish this, we installed a Heil PR781 Microphone, PL2T Boom and USBQ Adapter/Pre-Amp on our home office PC. The Heil USBQ is a USB sound card and microphone pre-amplifier which connects directly to the PR781 microphone to create a high-quality phone audio source which can be used with the FlexRadio-6700 SDR when operating remotely.

Bose SoundLink BluTooth Headset

Bose SoundLink Bluetooth Headset

The speakers our my home office PC are quite good but there are often times when a set of headphones are needed to hear weak signals. We choose a quality Bluetooth Headset from Bose for this purpose. The Bose SoundLink Headset is light weight, is wireless, has excellent fidelity and includes a very good microphone which can be used as an alternative to the Heil PR781. This headset is also very useful when operating from our Laptop Client PC from noisy locations outside our home (more on this in a future article).

SmartSDR DAX Control Panel

SmartSDR DAX Control Panel

The last pieces of the remote operating system are provided two applications which are part of the SmartSDR software package. The SmartSDR’s DAX Control panel provides remote audio connections for Digital Mode Software and the CW Skimmer decoder. Audio is provided by software “audio cables” for each of the FlexRadio SDR’s Slice Receivers and the active Tx Slice. SmartSDR DAX Audio IQ interfaces are also provided for each of the SDR’s Panadapters which permits software like CW Skimmer to monitor and decode a wide range of frequencies simultaneously.

SmartSDR CAT

SmartSDR CAT

The SmartSDR CAT application provides CAT interfaces on both our Client and Server PCs for applications which need to control or monitor what the FlexRadio-6700 SDR is doing. Many loggers and other applications are beginning to implement direct IP interfaces to the CAT channel of the FlexRadio 6xxx Series SDRs. This approach simplifies interworking between the software and the radio and appears to be more reliable than virtual COM-based CAT interfaces.

Client PC Running SmartSDR And The DXLab Suite

Client PC Running SmartSDR And The DXLab Suite (Home Office)

With all of the above elements in place, any client PC that can access our Home Network can be used to operate our station. The picture above shows SmartSDR and the DXLab Suite running on our Home Office PC. The remote emulations of the Rotator, CAT and Winkeyer interfaces are such that DXLab’s applications can fully operate our station as if they we running in our shack.

Client PC Running SmartSDR And The DXLab Suite - Right Monitor

Client PC Running SmartSDR And The DXLab Suite – Right Monitor

The picture above shows a closer view of my Home Office PC’s Right monitor (click on the picture to enlarge it). SmartSDR is running the upper left corner and I am listening to folks operate in the 2015 CQ WW DX CW Contest. The SDR is set on the 20m band and I have the CW Keyer which is built into SmartSDR running. The DAX Control Panel is running on the lower right corner of the screen and its setup for use with the CW Skimmer decoder. DXLab’s WinWarbler is running (top-center) which enables me to use the WinKeyer in the shack to send CW as well via the remote COM port associated with the WinKeyer. Below WinWarbler is the microHAM Developer Only application (accessed remotely via a TeamViewer connection to the Shack Server PC) which shows that I have both of our SteppIR DB36 Yagis are selected as a stack and pointed towards Europe. DXLab’s DXView Rotator Control application is running in the center-bottom of the screen so that we can turn our Yagis towards other parts of the world (rotators are controlled via another remote COM port). Finally, the client KPA500 Amplifier control application is running in the lower left corner to control the amplifier and to monitor the power out and SWR seen by the amplifier being used to operate remotely.

Client PC Running SmartSDR And The DXLab Suite - Left Monitor

Client PC Running SmartSDR And The DXLab Suite – Left Monitor

The picture above shows a closer view of the left monitor. DXLab’s logger, DXKeeper is running at the top/center of the screen. Below it is DXLab’s SpotCollector application which is monitoring spots of the many CW stations around the world that are operating in the contest. DXLab’s Commander applications is running in the lower-right corner of the screen and is monitoring the FlexRadio-6700 SDR’s slice Tx/Rx frequency as well as providing a control interface of the SDR to the rest of the DXLab Suite (via SmartSDR CAT). The Elecraft W2 Wattmeter client control application is just above commander. The W2 Wattmeter client application provides higher resolution power out and SWR monitoring for the remote setup. Bottom-center is DXLab’s Launcher application and just to the left of that is the KAT500 Auto-Tuner Client Control application. Finally, CW Skimmer is running on the left side of the screen.

CW Skimmer Operating Remotely

CW Skimmer Operating Remotely

As you can see, CW Skimmer is decoding a wide range of frequencies in the 20m CW sub-band. It is receiving its audio in IQ format via the SmartSDR DAX application. It is great fun to operate CW this way and I am finding myself making a lot more CW contacts now that I have the remote operating setup in my office.

The next post will provide some samples of remote operation in the form of videos. I will also share some information on setting up a Remote Operating Client on a laptop where screen space is more limited. We plan to take a trip outside our house to operate our station over the Internet and we plan to share information on how that is done. We will also provide future articles on how to setup CW Skimmer and Digital Modes (RTTY, PSK and JT65/JT9) on the HF Bands and use them remotely.

For now, we are really enjoying the freedom to operate our station remotely!

– Fred (AB1OC)