Tagged: qo-100

Understanding PLLs and their Importance when Receiving/Transmitting on QO-100

Over on YouTube Andreas Speiss has uploaded a video that explains what the geostationary QO-100 satellite is, and explains about the parts needed to receive and transmit to it. In particular Andreas goes into depth explaining the low noise block (LNB), and the PLL inside it. A PLL or phase locked loop is a common design used in RF electronics as it allows us to increase the frequency of crystal oscillators.

This PLL explanation ties into the fact that most commercial LNBs available do not have a stable enough crystal oscillator to properly receive or transmit the narrowband amateur radio signals used on QO-100. A PLL can increase the frequency of a crystal, but it will also increase the frequency drift and jitter/phase noise of the crystal. He notes that in later videos he'll show how to modify the LNB to improve these factors. We note that a commercially available stable LNB is the Bullseye LNB which we have posted about previously.

QO-100 Satellite Receiving Technology. And Explanation of a PLL

The Othernet Bullseye TCXO LNB for QO-100 Reception

Othernet have recently released their new "Bullseye" 10 kHz Ultra High Stability Universal LNB. It is currently on sale and available for US$39.95 + shipping on their store.

The LNB is designed for receiving QO-100 which is a popular geostationary amateur radio satellite positioned at 25.5°E which covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia. In the past we've seen several posts about people using RTL-SDRs to set up ground station monitors for this satellite, as well as special WebSDR software designed for QO-100 monitoring.

Typically an LNB with small satellite dish is used to receive QO-100 which downlinks at 10.489550 GHz. These LNB's have a built in LNA, and downconvert the signal into a frequency range receivable by an RTL-SDR. One problem is that most commercial LNBs were intended for satellite TV reception, and hence they do not need to use a very stable local oscillator. So reception of the narrowband signals on QO-100 can become a challenge if they are continuously drifting in frequency as temperature changes.

Othernet's new Bullsye LNB uses a 2PPM TCXO as the local oscillator which gives it high stability in the face of changing temperatures. To power it you'll need a bias tee or LNB power source capable of injecting 13 - 18v onto the coax line. The product description reads:

The Bullseye LNB is the world's most precise and stable Ku-band down converter. Even a VSAT LNBF costing hundreds of dollars more is no match for the performance of the Bullseye 10K LNB. Each unit is calibrated at the factory to within 1 kHz of absolute precision against a GPS-locked spectrum analyzer. As a bonus feature, the Bullseye 10K provides access to its internal 25 MHz TCXO through the secondary F-connector. This reference output can be used to directly monitor the performance of the TCXO over time.

  • Bullseye 10 kHz BE01
  • Phase locked loop with 2 PPM TCXO
  • Factory calibration within 1 kHz utilizing GPS-locked spectrum analyzers
  • Ultra high precision PLL employing proprietary frequency control system (patent pending)
  • Digitally controlled carrier offset with optional programmer
  • 25 MHz output reference available on secondary F-connector (red)
     
  • Input frequency: 10489 - 12750 MHz
  • LO frequency 9750/10600 MHz
  • LO frequency stability at 23C: +/- 10 kHz
  • LO frequency stability -20 - 60C: +/- 30 kHz
  • Gain: 50 - 66 dB
  • Output frequency: 739 - 1950 MHz (low band) and 1100 - 2150 (high band)
  • Return loss of 8 dB (739 - 1950 MHz) and 10 dB (1100 - 2150 MHz)
  • Noise figure: 0.5 dB

Over on his blog @F4DAV has uploaded a comprehensive review of the Othernet LNB which goes over the specs, construction and testing of the LNB. The review is an excellent read and he concludes with the statement:

As far as I know the BE01 is the first affordable mass-produced Ku-band TCXO LNB. Specifications are not entirely clear but these early tests suggest that it can be a game changer for amateur radio and other narrowband applications in the 10 GHz band. The stability and ability to recalibrate should allow even unsophisticated analog stations to tune to a 5 kHz channel and remain there for hours at a time. For SDR stations with beacon-based frequency correction, the absolute accuracy removes the need to oversample by several hundred kHz or to scan for the initial frequency offset.

The Othernet Bulleye High Stability LNB
The Othernet Bullseye High Stability LNB

Transmitting WSPR on QO-100 with a moRFeus and less than 4 mW Power

Thank you to Zoltan for submitting a short post about using a moRFeus to uplink WSPR to the Es'Hail-2 (QO-100) geostationary satellite with amateur radio repeater. moRFeus is a versatile US$99 signal generator and frequency mixer that can be controlled either by it's built in LCD screen, or via software on a Windows or Linux PC. It can generate a clean low phase noise tone anywhere between 85 to 5400 MHz, and can be used as a mixer for upconverting or downconverting signals. We have discussed moRFeus a few times before on this blog as we think it's a useful tool.

In his setup, Zoltan uses a QRP Labs U3S WSPR transmitter kit that was configured to transmit WSPR at 2m (144 MHz). It is not designed for transmitting the 2.4 GHz QO-100 uplink frequency. To get around that limitation, the moRFeus is used to upconvert the 144 MHz frequency into the QO-100 uplink band by mixing it with a 2,255,634.309 kHz signal. The resulting 2.4 GHz output signal from moRFeus is sent to an amplifier, 2.4 GHz band pass filter, and finally into a 5-turn LHCP helical feed mounted on a 1m parabolic dish.

Successful uplink was confirmed by a UK based WebSDR receiving the QO-100 downlink. Zoltan estimates that the total output power was only 4mW, and actually more like 1-2 mW due to losses in the coax feed.

WSPR uplink with moRFeus
WSPR uplink with moRFeus

Uplinking to QO-100 with a LimeNET Micro and LimeRFE

The LimeNet Micro is a is a $329 board that combines a Raspberry Pi 3 (compute module) together with a LimeSDR radio. The LimeRFE is an amplifier and filter board accessory designed to be used with LimeSDR units. When a LimeNET Micro and LimeRFE are used together, it is possible to create a transmit capable radio system that can be used for amateur radio.

Daniel Estévez has recently been doing several experiments with the LimeRFE, and this time he's managed to create an uplink capable ground station for the QO-100 amateur radio geostationary satellite. The LimeRFE can output 1W at 2.4 GHz and Daniel writes that with a low cost 2.4 GHz WiFi parabolic grid antenna this is more than enough power to work QO-100.

In terms of software, Daniel is using a Python script that communicates with the Limesuite API for PTT control. For transmitting IQ data generated by GNU Radio he uses limesdr_send. So far he's been able to successfully test a CW beacon, SSB voice and waterfall text generated by gr-paint.

LimeNet Micro + LimeRFE + 2.4 GHz WiFi Antenna = Full QO-100 Solution
LimeNet Micro + LimeRFE + 2.4 GHz WiFi Antenna = Full QO-100 Solution

 

Building a DIY 2.4 GHz Helical Feed for the QO-100/Es’Hail-2 Satellite

Over on his YouTube channel Adam 9A4QV has uploaded a short video that demonstrates his 2.4 GHz homemade helical feed designed to be used with a reflector (prime feed satellite dish) for QO-100/Es'Hail-2 satellite reception. The antenna is made from an old can, 2-turns of copper wire, and a plastic insulator to hold the turns in place. The two turns are wound in left hand circular polarization (LHCP), because when used with a satellite dish reflector it will result in right hand circular polarization (RHCP), which is the polarization QO-100 uses.

One of the most important parts of the video is when Adam shows how he matches the antenna to 50 Ohms. He notes that without matching the antenna won't work properly, and the return loss will be about 8 dB or even less, resulting in poor performance. With matching he obtains 30 dB return loss.

Helical feed for the 2.4 GHz QO-100 satellite

An RTL-SDR & SDRplay based WebSDR Designed Specifically for QO-100 (Es’Hail-2) Monitoring

Over on YouTube user [Radio Electronics] has uploaded a useful video showing how to install your own personal SDRplay or RTL-SDR based WebSDR for QO-100 (aka Es'Hail-2) reception. Es'Hail-2 is the first geostationary satellite with amateur radio transponders on board, and is positioned at 25.5°E which covers Africa, Europe, the Middle East, India, eastern Brazil and the west half of Russia/Asia.

The idea behind a WebSDR is to run your RTL-SDR QO-100 receiver on a remote Raspberry Pi (perhaps mounted close to the antenna on your roof etc). The Pi runs custom WebSDR software that has been created from scratch by [Radio Electronics] specifically for monitoring Es'Hail-2. Then you can access your QO-100 receiver from any device on your network that has a web browser (computer/phone/tablet etc). The interface of his WebSDR appears to be quite slick, which multiple QO-100 specific options and labels.

Quite a lot of work must have gone into this software which looks to be of high quality, so it is definitely worth checking out if you are interested in QO-100/Es'Hail-2 monitoring.

Es'Hail-2 QO-100 WebSDR
Es'Hail-2 QO-100 WebSDR

In the first video he first talks about various methods for downconverting the 10489.550 MHz QO-100 CW signal into a range receivable by the RTL-SDR or SDRplay. He then goes on to show the exact steps to install and run his WebSDR software on a Raspberry Pi 3.

In the second video he goes on to demonstrate the web browser interface highlighting the QO-100 specific features that he has implemented such as being able to compensate for any LNB frequency drift via a feature that can lock to the QO-100 PSK beacon.

es-hail-2 QO-100 WebSDR Part-1: INSTALLATION

es-hail-2 QO-100 WebSDR Part-2: OPERATION

Using SDR For QO-100 Satellite Operation

Es’hailsat, otherwise known as QO-100 is the first geostationary satellite with an amateur radio payload on-board. The satellite contains both a Wide Band transponder for experimental modes and DVB-S Digital Television and a Narrow Band transponder used mostly for SSB voice and some digital mode contacts with other amateur operators. If you’re unfamiliar with this satellite we’ve covered it in previous articles, like in [Es’hail Transponder Now Active]

While many choose to use a transverter connected to a traditional amateur transceiver, others have turned to use Software Defined Radios to complete their satellite ground stations.

[Radio Innovation] posted a video back in March showing his contact on QO-100 using a LimeSDR Mini as the 2.4 GHz transmitter and a 10 GHz LNB for the downlink.

Calling cq on QO-100 with LIMESDR

The PlutoSDR has been frequently seen used for QO-100 satellite operation on the Wide Band transponder due to its ease of DVB-S transmission utilizing software such as [DATV Express] but more recently there have been more and more operators turning to SDR for their day to day satellite operation.

It will be interesting to see how these stations evolve, perhaps by the time North America has access to a similar satellite, we’ll be prepared to operate it.