Teknik och hårdvara

FT4 via satellite with SDR-Console and IC-705

This is a simple guide for working FT4 mode via satellite with the help of SDR-Console software, a SDR receiver and Icom IC-705 as transmitter. The IC-705 can of course be replaced by any other radio that can be controlled via OmniRig.

The ”magic” is done by Omnirig. This smart little software can connect several software to one radio at the same time, in this case SDR-Console and WSJT-X.

This guide requires that you have basic knowledge of the following:

  • WSJT-X and FT4 operation
  • SDR-Console V3 satellite operation
  • IC-705 operation (or other radio if you like)
  • Audio piping between several software
  • Basic operation with OmniRig

Step 1 – Setup SDR-Console and IC-705 with correct frequency

First you need correct frequency for SDR-Console and IC-705. You can download and use the prepared files from this site.
Start SDR-Console and set the downlink (USB) to the satellite you would like to use. Set the IC-705 to the uplink of the satellite, note it has to be LSB-D (LSB with data mode).

Step 2 – Config WSJT-X

Start WSJT-X and config as following:

  • Rig should be Omnirig and your setup for IC-705
  • Mode should be ”None” to avoid WSJT-X to set the rig to USB-D
  • Soundcard Input should be the virtual audio from SDR-Console
  • Soundcard Output should be the IC-705 mic

Step 3 – Start Satellite External Radio in SDR-Console

Now start the ”Satellite External Radio” in SDR-Console. Select the same OmniRig radio as in WSJT-X. Select the correct uplink frequency and turn on Doppler correction in External Radio.
Now the magic happens! SDR-Console is starting to doppler correct the frequency of the IC-705 and WSJT-X reads the correct frequency from IC-705 in real time!

In this image you can see External Radio and WSJT-X with correct frequency:

Step 4 – Select correct RX frequency in SDR-Console

Select the correct downlink frequency in SDR-Console and enable Tracking in the Satellite Window for the satellite.
Now wait for the satellite to be in your footprint.

Step 5 – Find yourself on the satellite transponder

When the satellite is in your footprint, you need to manually adjust the TX-frequency (at the External Radio window) and RX-frequency, as the SDR-Console software does not have a ”tracking RX/TX VFO” function.

  • Find a free area on the satellite transponder
  • Turn your TX output to very low
  • Start transmitting FT4 or use the Tune function in WSJT-X
  • Adjust TX/RX so that your signal is in your RX bandwidth

Step 6 – Start calling CQ

Now you are ready to start calling CQ and making QSOs! Remember – use the minimum TX power, FT4 is very effective. And be sure not to call over a CW or SSB station.

How to use a 2nd instance of WSJT-X for RX of your own FT4 signal

If you would like to check your own FT4 signal (for testing and learning) it is possible to start a 2nd instance of WSJT-X as receiving only.

  • Create a new configuration in WSJT-X where Radio->Rig should be set to None and Audio Input should be the piped audio from SDR-Console.
    Save it to a name of your choice {your_configuration_name}
  • After you have started WSJT-X for the TX (see above) start a 2nd instance with this command in a cmd window:
    {path_to_your_wsjtx}wsjtx.exe –rig-name={your_configuration_name}
  • Now when you TX your FT4 signal the 2nd instance will decode your own signal. See the example below:

Finally, below is a recorded video of a test via satellite AO-73 decoded with a 2nd instance.
If you have any questions about this setup please contact AMSAT-SM (Lars SM0TGU) at info@amsat.se

Satellitnyheter Teknik och hårdvara

AMSAT SA Dual Band 70cm/2M Yagi Mark II

AMSAT SA has launched Mark II of its dual band 70 cm/2 m handheld beam antenna with a new, easier to hold handle and improved coaxial terminations. The Yagi has been retuned for maximum performance in the amateur radio 2 m and 70 cm satellite bands. The coax cable is terminated crimped brass lugs instead of being soldered making it environmentally more robust. The driven element has been adjusted to accommodate the change in the connection. More about the Yagi. The antenna has a 50-ohm designed driver. The Yagi has a unique element called an ’Open Sleeve’ which is a director very close to the driven element. The driven element is sized for 2 m. When operating on 70 cm the ’Open Sleeve’ acts as part of the driven element on 70 cm (the third harmonic of 2 m).

The original concept was developed in 1946 by Dr J T Bolljahn of the Stanford Research institute but was not introduced into amateur radio until the 1950s. The AMSAT SA version is based on a design by DK7ZB with modifications by WB5CXC. The first South African version was a collaboration between Guy Eales, ZS6GUY and Gary Immelman, ZS6YI. It was developed for YOTA 2018 where young people successfully used the antenna operating satellites using hand-held transceivers.

The mechanical structure was redesigned by Gary Immelmann ZS6YI. A choke around the boom was added to isolate the antenna from the coax and reduce the effect human contact has on the antenna. A handle was added on the boom end which makes it more comfortable to hold and further isolates the antenna from the handler. The AMSAT SA Yagi is manufactured in one of Gary Immelmann’s factories in Vereeniging. It has two elements on 145 MHz and 3 elements on 435 MHz.

For its size, the antenna has excellent gain: 145 MHZ: 4.12 dBd or 6.3 dBi and 435 MHz: 6.23 dBd or 8.4 dBi. The Yagi is broadband with measured SWR being almost flat over the entire bands. The antenna is plug and play, no tools are needed except for soldering on a connector to suit the application. It comes complete in a carry bag with full instructions. This antenna can be assembled and dissembled in minutes. The price of the MKII Yagi is R400 for AMSAT SA and SARL members. Non-members pay R500 (approximately $36.75 US). The courier charge is R120 (approximately $9 US, Postnet to Postnet). Ask for a quote for other courier options. Find more details and order forms on http://www.amsatsa.org.za/

[ANS thanks AMSAT SA for the above information]

Teknik och hårdvara

Avoid heading failure for Rot2Prog

The Rot2Prog rotor controller, sold with the popular RAS rotor series, have a nasty bug if using the rotor with a computer. I not sure when it happens, I have not been able to reproduce it on demand, but in some condition the ”Heading adjust” (PP in the setup mode of the controller) seams to be set from the computer to a totally wrong heading….

To avoid this problem I think (but not 100% sure) this is the way to handle the controller:

  • Always turn off the Rot2Prog before shutting down the computer!
  • Turn off the Rot2Prog if you are not using it and the computer is on
  • If you are using the Rot2Prog manually, or using the setup menu, and the computer is on be sure that you do not have any controlling software (like PstRotator) running at the same time

But… If you get this error it is easy to adjust the heading with the PP ”Heading Adjust”, turn the rotor to north and then reset the Rot2Prog with ”On + F”.

Teknik och hårdvara

Transceivers for Amateur Radio Satellites


This is a list of VHF/UHF transceivers that can be used for Amateur Radio Satellites. At the moment I choose only to list:

  • Rigs that have both VHF and UHF (HF as bonus) and all mode
  • Full Duplex Base Station rigs
  • Non Full Duplex smaller rigs that can be used mobile or as portable

Many of the rigs are discontinued. FM only mobile rigs and handheld can be added later to this list but can be found on this page from 2017. In the table below the weight is listed, because that was data I was interested in when I did the summary. For all other data – please follow the link to RigPix. As you see Icom, Kenwood and Yaesu are the main brands.

This list will never be complete in any way but maybe can help if you looking for old used rigs. All info is from the excellent RigPix Database.

Full Duplex All Mode Base Station VHF/UHF transceivers

NameWeight (kg)Note
IC-97004.7D-Star, SDR

Mobile or Portable All Mode VHF/UHF transceivers
(not full duplex, all has HF)

NameWeight (kg)Note
IC-71002.7 (with front panel)
IC-7051.1D-Star, SDR, Battery
See our posts about IC-705
Teknik och hårdvara

Working satellites with IC-705 PstRotator or SDR-Console

This is a guide how to working satellites with the IC-705 or similar rig. When trying to understand the IC-705 I needed to write down how to use it – so this is how this post was born. I will try to explain 3 different user scenarios, each have a case for FM- and linear satellites :

  • Working stand alone (portable) without computer control
  • Working with SDR-Console for doppler adjust and a SDR as receiver
  • Working with PstRotator for doppler adjust

The IC-705 satellite memory examples and file can be found here.
Please contact me if you see anything that will not work in the following user cases – I have limited knowledge.

Setting up PstRotator

I will not explain how to use and set up PstRotator – the PstRotator manual is very good. The settings for Omnirig is like this:

And a typical layout for PstRotator Satellites Tracking is like this (and for reference image for the text below):

Case 1: Using IC-705 stand alone without computer control

FM satellites

  • Select split memory for the satellite in IC-705.
  • If needed adjust the RX frequency with the VFO knob (look at the waterfall).
  • Adjust the TX frequency for doppler when transmitting with VFO knob. Use a printed frequency chart for help.

Linear satellites with SSB transponder
(I have never tried semi-duplex on linear satellites before so not sure if this works)

  • Select split memory for the satellite in IC-705.
  • Adjust the RX frequency with the VFO knob to find a free space on the transponder (look at the waterfall).
  • Adjust the TX frequency (press PTT and use the VFO knob) to the correct frequency on the uplink. Use a printed frequency chart for help.
Case 2: Using IC-705 with SDR-Console v3

In this case the IC-705 is working as the transmitter with full doppler control and a SDR as receiver, also with doppler control.
This is my primary working setup for now!

FM satellites

  • Select the downlink frequency in SDR-Console for your SDR receiver and enable tracking in the satellite window, this will doppler control your RX.
  • Select the uplink memory for the satellite in IC-705 to get correct CCTCS tones.
  • Select the uplink frequency in SDR-Console, it will be transferred to External Radio windows.
  • Start External Radio in SDR Console for doppler control – no need to do anything on the IC-705 – just transmit.

Linear satellites with SSB transponder

  • Select the downlink frequency in SDR-Console for your SDR receiver and enable tracking in the satellite window, this will doppler control your RX.
  • Select the uplink frequency in SDR-Console, it will be transferred to External Radio windows.
  • Adjust the RX frequency at SDR Console to find a free space on the transponder (look at the waterfall).
  • Start External Radio in SDR Console for doppler control.
  • As SDR Console does not link (track) up/downlink VFOs – adjust the TX frequency on the IC-705 with the VFO knob to the correct frequency on the uplink. Doppler is corrected also during TX. Use a printed frequency chart for help.
    You can also adjust the frequency with the mouse wheel in at the External Radio windows. I find this better then using the VFO knob on the radio.

    In late 2021 I have made a virtual VFO control that is working well and this is the way I’m working all my QSOs now.
    Please see this post on my GitHub for more info.

Case 3: Using IC-705 stand-alone with PstRotator

In this case PstRotator sets the correct frequency and mode on the IC-705 and has doppler control for both RX and TX. You are working IC-705 stand-alone as semi-duplex.
Note! I’m not using this setup for now.

FM satellites

  • Select the satellite from PstRotator Favorites. Correct frequency, mode and subtone are now set in IC-705 VFOs.
  • Press the ”UP+DN” on PstRotator. Doppler is now adjusted on both RX and TX.
  • No need to do anything on the IC-705 – just transmit and listen.

Linear satellites with SSB transponder

  • Select the satellite from PstRotator Favorites. Correct frequency and mode are now set in IC-705 VFOs.
  • Press the ”UP+DN” on PstRotator and check that VFO linking are set to ”Reverse”. Doppler is now adjusted on both RX and TX and the VFOs are linked.
  • Adjust the RX frequency with the VFO knob to find a free space on the transponder (look at the waterfall). The TX is linked and will have correct frequency.
  • Change the VFO linking to ”Not linked” on PstRotator. This means that both TX and RX are still doppler adjusted but the TX frequency is locked (fixed). If needed you can adjust the RX frequency with the VFO knob on the IC-705.

Finally this is a short video when using the tiny GPD MicroPC with PstRotator and IC-705 as a portable computer controlled doppler adjustment.

Teknik och hårdvara

VHF Handboken är uppdaterad

I November 2020 gavs det ut en ny version av VHF Managers Handbook på IARU Region 1:s hemsida, V9.0. där man hittar ändringar runt bandplan och satellitallokering på 436.000 MHz – 438.000MHz gällande samexisterande digitala trafiksätt

Handboken har uppdaterats hur simplex DATV trafik och experimentell dataöverföring används på 70cm i samma bandplan där satellitfrekvenserna finns.

Handboken har uppdaterats för användningen av enbart simplex DATV/experimentell dataöverföring samt förhållandet och prioritet till satellittrafik i samma bandplan.

I handboken har man nu även beslutat att på 70cm inte längre tillåta äldre ATV och andra ”digitala” trafiksätt kräver mycket bandbredd.

Nyare digitala trafiksätt möjliggör att man kan använda UHF/VHF banden eftersom den bandbredd som krävs är betydligt smalare, dvs. man är inte enbart hänvisad till att använda mikrovågsbanden eftersom bandbredden som krävs ryms nånstans inom bandplanen för respektive VHF UHF band. Dvs. samexisterande trafik förväntas behöva plats på t.ex 436-438MHz.

Exempel på icke-satellit simplex digital trafik som kan dyka upp på 436-438MHz och samexistera på 70cm är enligt standarder DATV DVB-S, RB-ATV.
DATV DVB-S används med en symbolhastighet på 2 M S/sec och bandbredden blir 2MHz.
RB-ATV kan användas med en symbolhastighet på 333 K S/s och bandbredden blir 450kHz.

Det finns andra digitala trafiksätt som t.ex New Packet Radio (NPR) med varierande bandbredd 100kHz till 500kHz och som troligen passar in som experimentell dataöverföring men det finns redan en 200kHz bred allokering för datatrafik på 433.600-434.000MHz så NPR trafik bör återfinnas där.

Här är några klipp ur VHF handboken där ändringarna på 70cm syns.


1.5.1 Footnote (c ) to:
As of 1-Jan-2021 Analogue ATV and SATV is no longer permitted in the 430-440 MHz band.

ATV operators are encouraged to use the microwave allocations where available, but may use narrower bandwidth DATV modes in the 436-438 MHz band.
See 1.5.4 for further guidance for DATV and experimental Data usage.
In case of interference between DATV/Data and the Amateur Satellite Service, the Satellite Service shall have priority.

1.5.4 DATV and Experimental Data usage in the 436-438 MHz Band (VGC 2020)
If the 436-438MHz amateur satellite section is used for DATV or other experimental Data developments, it
shall be on the following basis:
• DATV (like Voice) Repeater outputs are not permitted
• DATV Internet gateways are not permitted
• DATV Repeater inputs are permitted (eg for cross band usage)
• DATV Simplex usage is permitted
• Transmission times by DATV/Data users should be as short as possible
Any DATV and adhoc simplex Data usage of similar bandwidths to DATV, should be compliant with the
Region 1 Technical Recommendations for DATV in Section-9.4 and in particular the maximum bandwidth.
No other fixed infrastructure for nodes, gateways, DV hot-spots or repeaters are permitted in 436-438MHz.

Här är några klipp från IARU 2020 konferensen:

Recommendations for Technical Recommendations:
a) Rename Section-9 title to Amateur Television (remove ‘wide band’)
b) Remove Sec 9.1 for AM TV in 435 MHz
c) Remove Sec 9.2 for 435 MHz medium BW ATV
d) Remove 9.4.1 re 435 MHz Fast scan ATV standard
e) Remove 9.4.2 re 435 MHz SATV standard
f) Remove 9.4.3 Fax Standard (also redundant)

70cm bandplanen på SSA.SE med fotnot.

435,000 – 436,000 20 kHz Alla moder Exklusivt satellitsegment (e)
436,000 – 438,000 Alla moder Satellitsegment och DATV/Data(e)
(e) Sändning från DATV repeatrar skall inte förekomma i bandet 436 – 438 MHz.

Några länkar: