Tagged: digital amateur television

A LimeSDR Mini Based Es’Hail-2 DATV Ground Station Uplink

Daniel Estévez has posted on the LimeSDR Mini CrowdSupply blog about his ground-station build for the Es'Hail-2 satellite. Es'Hail-2 is the first geostationary satellite with amateur radio transponders on board. The LimeSDR Mini is a $159 RX/TX capable SDR with 10 MHz to 3.5 GHz frequency range.

The Es'Hail-2 satellite is positioned at 25.5°E which is over Africa. It's reception footprint covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia. There are two amateur transponders on the satellite. One is a narrow band linear transponder which uplinks from 2400.050 - 2400.300 MHz and downlinks from 10489.550 - 10489.800 MHz. Another is a wide band digital transponder for digital amateur TV (DATV) which uplinks from 2401.500 - 2409.500 MHz and downlinks from 10491.000 - 10499.000 MHz.

Daniel's ground station uses a LimeSDR Mini running on a Beaglebone Black. A 2.4 GHz WiFi parabolic grid antenna is used to transmit to the satellites digital amateur TV uplink. In order to generate enough power for the uplink transmission a GALI-84 amplifier chip is cascaded with a 100W power amplifier. All the electronics are enclosed in a watertight box and placed outside.

A LimeSDR Mini Based Es'Hail-2 DATV Uplink Ground Station
A LimeSDR Mini Based Es'Hail-2 DATV Uplink Ground Station

Amateur Radio on the Es’hail-2 Satellite Explained on YouTube

Over on YouTube Tech Minds has posted a video explaining what Es'hail-2 satellite is and why it is interesting for hams and SDR users. Briefly Es'hail-2 is a recently launched geostationary TV satellite that covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia.

What's special about it is that apart from the TV transmitters, it also contains the worlds first amateur radio transponder in geostationary orbit. So amateur radio users within the region covered by the satellite can simply point their antennas to a fixed position in the sky to transmit to the satellite, and the signal will be rebroadcast over the entire covered area. With a simple LNB, satellite dish and SDR the signals can be received.

After explaining Es'hail-2 Tech Minds also shows a demo of Es'hail-2 radio traffic using a public WebSDR.

The Worlds First Geostationary Satellite For Ham Radio - Es'Hail 2 - Qatar OSCAR-100

Es’hail-2 Amateur Transponder Now Active

Es'Hail 2 Coverage
Es'Hail 2 Coverage from Amsat-UK

Es'hail 2 was launched last November and it is the first geostationary satellite to contain an amateur radio transponder. The satellite is positioned at 25.5°E which is over Africa. It's reception footprint covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia. There are two amateur transponders on the satellite. One is a narrow band linear transponder which uplinks from  2400.050 - 2400.300 MHz and downlinks from 10489.550 - 10489.800 MHz. Another is a wide band digital transponder for amateur digital TV which uplinks from 2401.500 - 2409.500 MHz and downlinks from 10491.000 - 10499.000 MHz.

Although it launched last year it takes several months for the engineers to test and qualify the transponder for use. Over the last few weeks the transponder was intermittently active during the testing, but now since Feb 13 2019 the amateur transponder has finally been fully activated for amateur radio use.

To receive it with an RTL-SDR or most other SDRs an LNB is required to receive the 10 GHz signal and downconvert it into a frequency range that most SDRs support. Typically an Octagon LNB is used, and these are easy to find and cheap as they are often used for satellite TV.

From various reports seen on Twitter, it seems that the signal is strong enough that a satellite dish is not required for receiving - simply pointing the LNB directly at the satellite is enough.

If you can't set up a receiver, there is an OpenWebRX livestream of the Es'hail 2 narrowband channel that has been set up by Zoltan/RFSparkling which is available at sniffing.ddns.net:8073 (note the server can only handle 8 users at a time, so try again later if it's busy). Also as pointed out by KD9IXX on Twitter, there are also several websdr.org servers receiving and streaming Es'hail2 including an Airspy based one run officially by AMSAT-DL.

Es’hail-2 Transponder Tests + Narrow Band Web Stream

Es'hail 2 was launched last November and it is the first geostationary satellite to contain an amateur radio transponder. The satellite is positioned at 25.5°E which is over Africa. It's reception footprint covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia.

Although the satellite was launched last year, turning on the amateur transponders has been slow because the commercial systems of the satellite have higher priority for testing and commissioning. However, within the last day the Es'hail 2 team have now begin testing the amateur transponder, and the test signal has been successfully received by several enthusiasts (just check out the Twitter feed). There also appears to have already been a suspected pirate CW signal broadcasting "WELCOME DE ES2HAIL". Actual uplink use of the satellite is not currently wanted, and from the Amsat forums one of the engineers writes:

Before the IOT starts there will be a TRR (test readyness review) in front of the customer. All the testplans and test-specifications will be reviewed. When the test is done there will be a TRB (test readyness board). In the TRB they have to show/present all the measurement results (e.g. inband performance like Gainflatness, Groupdelay... aso.) and compare these results with the specification in the contract. Each unwanted signal makes the measurement difficult and needs to be explained or leads to a so named NCR (non conformance report).

The IOT will be done in shifts/nightshifts and with unwanted signals (if not explain able) some measurements needs to start again and again and leads in addition to a delay for the handover and operation of the satellite.

Maybe that helps to understand why it is really important to have only the IOT uplink signal.

To measure the pattern of each antenna the satellite will be moved east/west by the propulsion system of the DS2000 Bus and the signal level is measured by the IOT station on ground (some cuts) .

The commercial beacon can maybe be switched from LEOP Omni antenna to on station antenna when the satellite is placed in the final slot. This should be the reason for the change of the commercial Ku Band beacon signal level the last days.

If you are interested in receiving Es'hail 2, but live outside the footprint, or don't have a receiver then you can use Zoltan's OpenwebRX live stream of the narrow band portion of the Es'hail 2 downlink. At the moment the beacon doesn't appear to be transmitting, but we expect it to be on and off during the next few days. In his set up he uses an RTL-SDR V3, Inverto LNB, 90cm dish, a DIY bias tee and a Raspberry Pi 3.

He also took a recording of the pirates CW transmission shown in the video below.

Es'hail-2 live, CW signal 2019.01.17.

Es-hail 2 test transmission
Es-hail 2 test transmission

Es’hail-2: First Geostationary Satellite with Amateur Radio Transponders Successfully Deployed

Today SpaceX have successfully launched and deployed the Es'hail-2 satellite which is now in geostationary orbit. This launch is special for amateur radio enthusiasts because it is the first geostationary satellite that contains an amateur radio transponder on it. The satellite is positioned at 25.5°E which is over Africa. It will cover Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia. Unfortunately, North America, Japan, most of South America, Australia and NZ miss out.

Coverage of Es'hail 2
Coverage of Es'hail 2

The satellite has a two bandwidth segments, a 250 kHz narrow band for modes like SSB, FreeDV, CW, RTTY etc, and a 8 MHz wide band for digital amateur TV (DATV) modes like DVB-S and DVB-T.

The downlink frequencies are at 10 GHz so a low cost TV LNB could be used as the antenna. For receiving the narrowband modes, an RTL-SDR or similar SDR could be used, and for the 8 MHz DATV modes a standard DVB-S2 set top box can be used to receive and decode the video. For uplink, the transmission frequency is at 2.4 GHz.

According to the commissioning order of the satellite, it is expected that the AMSAT transponders will be activated only after all tests have been passed, and after other higher priority commercial telecommunications systems have been activated. This is expected to take about 1-2 months.

2018: Es'hail-2 and its amateur radio payload - Graham Shirville (G3VZV) & Dave Crump (G8GKQ)

Videos Showing Rpidatv in action

A few days ago we posted about the release of Rpidatv, a program that allows a Rapberry Pi to transmit DATV without the need for any additional hardware. DATV stands for Digital Amateur TV, and can be received with an RTL-SDR using a program called leandvb.

Over on YouTube, the programmer of Rpidatv (Evariste F5OEO) has uploaded a video that shows a Rpidatv + leandvb system in action. The video demonstrates the touch screen GUI which can be used if a touch capable LCD screen is connected to the Raspberry Pi. It also shows the whole system in action with a video being transmitted from the Raspberry Pi camera to a Linux PC with an RTL-SDR running leandvb.

rpidatv with leandvb

Another video uploaded to YouTube by Qyonek also shows Rpidatv + leandvb in action.

Testy rpidatv + leandvb

Transmitting DATV with a just a Raspberry Pi

All the way back in April 2014 we first posted about how the Raspberry Pi was able to transmit FM by cleverly modulating one of it’s GPIO pins. Later in October 2015 F5OEO expanded this idea and created software that allowed the Raspberry Pi to transmit not only FM, but also AM, SSB, SSTV and FSQ. Soon after some filter shields such as the QRPi were released to try and cut down on the spurious emissions caused by transmitting using this method.

Now F5OEO has once again taken this method a step forward and has created software capable of allowing the Raspberry Pi to transmit Digital Amateur TV (DATV). The software is called Rpidatv, and can be downloaded from https://github.com/F5OEO/rpidatv. It can be run from the command line, or via a touch graphical interface if you have a touchscreen LCD screen. DATV is a DVB-S broadcast and can be decoded with an RTL-SDR by using the leandvb software which is bundled together with the Rapidatv software. Previously we’d posted about how the International Space Station intends to one day transmit DATV and that it can be decoded with an RTL-SDR.

F5OEO writes that the software is capable of generating a symbol rate from 64k symbols to 1M symbols, which is enough to transmit one video with good H264 encoded quality. He also writes that using a low symbol rate may be useful for long distance transmissions as the signal will take up a smaller bandwidth. For example a 250K symbol transmission would only need 300kHz of bandwidth. He writes that this type of transmission could easily be used in the ISM band to replace WiFi video for FPV, but that at the moment video latency is about 1 – 2 seconds and is still being improved.

Once again we remind you that if you intend to transmit using these methods where a GPIO pin is modulated, then you MUST use a bandpass filter at the frequency you are transmitting at, and that you must be licensed to transmit on those frequencies.

A DATV transmission received from a Raspberry Pi transmitter.
A DATV transmission received from a Raspberry Pi transmitter.

Receiving Digital Amateur TV from the ISS with an RTL-SDR

The international space station (ISS) is currently testing transmission of a DVB-S digital video signal. At the moment only a blank test pattern is transmitted, but one day they hope to be able to transmit live video properly for the purposes of making live contact with astronauts, and possibly to stream video of scientific experiments, extravehicular activities, docking operations, or simply live views of the Earth from space.

Over at www.pabr.org the author Pabr has been experimenting with using an RTL-SDR dongle for the reception of these digital amateur TV (DATV) signals. Over on Reddit he also posted some extra information about his work:

I have been able to receive DVB-S broadcasts from the ISS (known as HamVideo or HamTV) with a high-gain 2.4 GHz WiFi antenna ($50), a custom downconverter ($65), a R820T2 dongle, and a software demodulator (Edmund Tse’s gr-dvb). I used to think this could only be done with much more expensive SDR hardware.

It is commonly known that rtl-sdr dongles do not have enough bandwidth to capture mainstream satellite TV broadcasts, but the ISS happens to transmit DVB-S at only 2Msymbols/s in QPSK with FEC=1/2, which translates to 2 MHz of RF bandwidth (2.7 MHz including roll-off).

Before anyone gets too excited I should mention that:

  • This was done during a favourable pass of the ISS (elevation 85°)
  • With a fixed antenna, only a few seconds worth of signal can be captured
  • Demodulation is not real-time (on my low-end PC)
  • Currently the ISS only transmits a blank test pattern.

I now believe the BoM will be less than $50 by the time the ISS begins broadcasting interesting stuff on that channel.

Pabr uses a 2.4 GHz parabolic WiFi antenna to receive the signal. He writes that ideally a motorized antenna tracker would be used with this antenna to track the ISS through the sky. Also since the DATV signal is transmitted at around 2.4 GHz, a downconverter is required to convert the received frequency into one that is receivable with the RTL-SDR. The DATV decoder is available on Linux and requires GNU Radio.

Receiving DATV from the ISS
Receiving DATV from the ISS with an RTL-SDR