SignalsEverywhere: Testing out NooElecs PCB L-Band Patch Antenna

Over on his YouTube channel Corrosive from the SignalsEverywhere YouTube channel has uploaded a video where he tests out the new US$29.95 NooElec PCB patch antenna for receiving L-band satellite signals. In the video he shows how it can be combined with one of their SAWBird L-band low noise amplifiers in order to receive L-band satellite signals such as Inmarsat STD-C and AERO.

We note that our own RTL-SDR Blog Active L-band patch antenna will be ready to ship out before the end of this month, and while waiting for it we are currently having a preorder sale for US$34.95 including free shipping over on our store. For US$34.95 our patch antenna is fully contained in a waterproof enclosure, includes an LNA built in, and comes with several mounting options, so we believe that it is really a great deal. The patch design is based on the Outernet ceramic patch that was compared against the NooElec PCB patch shown in Corrosives video, so performance will be very similar.

Nooelec NEW Inmarsat Patch Antenna with Airspy SDR

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SDR in the Local Newspaper: Investigating an RF Dead Spot for Car Key Fobs

Reddit user [SDR_LumberJack] writes how he was recently featured in his local newspaper [Part2] in Ontario, Canada thanks to his efforts in helping to hunt down the cause of an RF deadspot with an SDR. He began his journey by reading a story in his local newspaper called the [Windsor Star]. The story was about locals having found a ‘dead-spot’ for car key-fobs. In the dead-spot key-less cars wouldn’t start, key-fobs wouldn’t unlock cars, and alarms would go off.

Being intrigued by the story [SDR_LumberJack] investigated by driving around with an RTL-SDR, HackRF and a laptop running SDR#. Eventually he found that there was what appeared to be a WBFM Broadcast radio station interfering at 315 MHz. This frequency happens to fall into the ISM radio band that used by car remotes and key-fobs. The exact source of the interference hasn’t been nailed down just yet though.

While it’s possible a broadcast station is at fault it is also possible that his SDR was just overloading, causing broadcast FM imaging. Perhaps a WBFM filter could be used to prevent signal imaging that could interfere with the investigation.

Hopefully [SDR_LumberJack] will continue his investigation and we’ll get an update on this story.

If you’re interested, back in 2016 we posted a very similar story about the exact same thing happening at a car park in Brisbane, Australia. The conclusion to that story was that the dead-spot only occurred in particular locations in the car park, and this was due to the shape of surrounding building causing the RF signals to reflect off the walls and distort the signal.

SDR_LumberJack in the local newspaper
SDR_LumberJack in the local newspaper
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The TangerineSDR: A Scientific SDR For Space Weather Radio and More

Over on YouTube the Ham Radio 2.0 has uploaded an interview with Scotty (WA2DFI) from TAPR who talks about a new software defined radio called the TangerineSDR that is expected to be released mid-2020. 

The TangerineSDR will focus on scientific use cases such as the HamSci Personal Space Weather Station, ground satellite stations, academic research and RF sniffing. The goal is to have a modular SDR that can be produced cheaply for educational institutions, whilst having the capability to be upgraded to a high performance version for the space weather station.

The TangerineSDR is a Modular Software Defined Radio Project with the following objectives:

  1. Development of SDR radios that allow experimentation in a variety of radio modes.
  2. Provide support to unaffiliated other groups that need these radios to support their mission.
  3. To provide hardware modularity so that the user can have a functioning radio with different subsets of the possible components.
  4. To allow varying performance so that beginners can have a functioning radio with a minimum of parts, yet allow an expert user more functionality as needed.
  5. To allow users to experiment with differing configurations of data collection, networking, transport and visualization.

In the Video Scotty shows off a mock-up of the TangerineSDR. The video description by Ham Radio 2.0 reads:

Presented at the TAPR Digitial Communications Conference of 2019, Scotty, WA2DFI, shows us a mock-up of a newly designed radio for Space Weather, and many other things, dubbed the Tangerine SDR. This modular radio is planning to be in production by mid-2020, with a working prototype to show at the 2020 Orlando Hamcation. Take a look at this short video and let me know what you think.

Tangerine Scientific SDR Space Weather Radio - FirstLook

For more information see tangerinesdr.com and the TangerineSDR mailing list.

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New Product in Store: RTL-SDR Blog Magnetic Whip Antenna Set (Great for KerberosSDR Direction Finding)

We've recently released a new Magnetic Whip Antenna Set in our store. The set consists of a heavy duty magnetic mount antenna base with 2M RG59, a 9.5cm fixed whip antenna (usable from 400 MHz to 2 GHz+), and a 17cm to 1m telescopic whip (usable from 100 MHz - 400 MHz).

Click Here to Visit our Store

The antenna set costs US$14.95 each with free shipping. And if you buy four sets you will receive a 15% discount. Currently available to ship worldwide right now from our warehouse in China, and they will be on Amazon in 2-3 weeks.

One application of our KerberosSDR 4-Tuner Coherent RTL-SDR is radio direction finding. This requires four quality omni-directional antennas. We were disappointed to find that there were no high quality magnetic whip antennas available on the market for a low price that we could use with KerberosSDR so we made our own.

The magnetic base is designed carefully with conductive metal that is properly connected to the shield of the coax cable. Most cheap antenna bases just leave the shield connection floating and this causes insufficient coupling to the underlying ground plane resulting in poor performance and poor results when it comes to direction finding and reception.

We've tested this set with KerberosSDR and it is known to work well. The antenna can also of course be used for any other receiving purpose if you prefer to use a whip antenna over our multipurpose dipole antenna set.

In the first two images in the image slider below you can see a comparison between a black base that is not properly bonded to the coax shield, vs the RTL-SDR Blog silver base which is correctly bonded to the coax shield. Both tests used the 9.5cm whip antenna. You can see that the RTL-SDR Blog silver base provides a much lower noise floor and higher signal SNR due to the better ground plane. Also we note that when placing the antenna bases on a metallic surface to create a larger ground plane, the black base showed no further improvement, whereas the RTL-SDR Blog silver base did.

The final three images in the slider show the SWR plots of the two whips on the base. We can see that the 9.5cm whip provides an SWR of less than six below 412 MHz. The telescopic whip can be adjusted to provide better SWR for lower frequencies.

RTL-SDR Blog Antenna Base (Coax shield properly connected to base)
Generic Black Antenna Base (Coax shield not connected to base)
9.5cm Whip SWR Plot
Telescopic Whip Collapsed SWR Plot
Telescopic Whip Fully Expanded SWR Plot
RTL-SDR Blog Antenna Base (Coax shield properly connected to base) Generic Black Antenna Base (Coax shield not connected to base) 9.5cm Whip SWR Plot Telescopic Whip Collapsed SWR Plot Telescopic Whip Fully Expanded SWR Plot
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International Space Station SSTV Event Scheduled for October 9 and 10

The International Space Station (ISS) periodically schedules radio events where they transmit Slow Scan Television (SSTV) images down to earth for listeners to receive and collect. This time they have scheduled SSTV images for October 9 09:50 - 14:00 GMT and October 10 08:55-15:15 GMT.

With an RTL-SDR and a simple V-Dipole from our RTL-SDR V3 antenna kit it is possible to receive these images when the ISS passes over. ISS passes for your city can be determined online, and the SSTV images can be decoded with a program like MMSSTV.

AMSAT-UK writes:

Russian cosmonauts are expected to activate Slow Scan Television (SSTV) image transmissions on 145.800 MHz FM from the International Space Station on Wednesday/Thursday, October 9/10.

This is the schedule for the planned activation of the MAI-75 SSTV activity from the ISS.
• Oct 9 09:50-14:00 GMT
• Oct 10 08:55-15:15 GMT

Transmissions will be sent on 145.800 MHz FM in the SSTV mode PD-120. Once received, images can be posted and viewed by the public at http://www.spaceflightsoftware.com/ARISS_SSTV/index.php

ISS SSTV uses a Kenwood TM D710E transceiver which is part of the amateur radio station located in the Russian ISS Service Module.

Please note that SSTV events are dependent on other activities, schedules and crew responsibilities on the ISS and subject to change at any time. You can check for updates regarding planned operation at:
ISS Ham https://twitter.com/RF2Space
ARISS Status https://twitter.com/ARISS_status
ARISS SSTV Blog https://ariss-sstv.blogspot.com/
AMSAT Bulletin Board http://www.amsat.org/mailman/listinfo/amsat-bb

Read the MagPi article Pictures from space via ham radio
https://www.raspberrypi.org/magpi/pictures-from-space-via-ham-radio/

ISS SSTV info and links https://amsat-uk.org/beginners/iss-sstv/

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An Introduction to Pagers with the HackRF PortaPack and an RTL-SDR

Over on YouTube user HackedExistence has uploaded a video explaining how POCSAG pager signals work, and he also shows some experiments that he's been performing with his HackRF PortaPack and an old pager.

The Portapack is an add on for the HackRF SDR that allows the HackRF to be used without the need for a PC. If you're interested in the past we reviewed the PortaPack with the Havok Firmware, which enables many TX features such as POCSAG transmissions.

POCSAG is a common RF protocol used by pagers. Pagers have been under the scrutiny of information security experts for some time now as it is common for hospital pagers to spew out unencrypted patient data [1][2][3] into the air for anyone with a radio and computer to decode.

In the video HackedExistence first shows that he can easily transmit to his pager with the HackRF PortaPack and view the signals on the spectrum with an RTL-SDR. Later in the video he explains the different types of pager signals that you might encounter on the spectrum, and goes on to dissect and explain how the POCSAG protocol works.

Intro to Pagers - POCSAG with HackRF

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Using a PlutoSDR to compare FreeDV Digital Voice with other Modes

Over on YouTube user Adrian M has uploaded a video where he compares the HF amateur radio digital voice mode known as FreeDV against other common voice modes such as USB, AM, FM and QPSK. To perform the test he uses a PlutoSDR, a GNU Radio program and a GUI called qradiolink.

FreeDV is an open source amateur radio digital voice mode that uses Codec2 compression. It's designed to compress human voice and works with narrow bandwidths and with weak signal power.

In the demonstration Adrian reduces the TX power slowly for each mode, so you can see what the voice sounds like at high and low signal power. The FreeDV mode is not high fidelity in terms of audio quality, but the voice remains able to be copied at low power when the other modes could not.

Transmit and receive FreeDV 1600 and 700C with SDR hardware

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A NanoVNA 2.0 is in the Works: Same Price, Frequency Range up to 3.5 GHz, Higher Dynamic Range

Previously we've been posting about the NanoVNA which is an open source VNA project by @edy555 / ttrftech that has recently become extremely affordable at less than US$50 for a fully assembled unit thanks to Chinese manufacturing (or a little more if you order it via Amazon).

Over on the NanoVNA groups.io forums we've seen discussion about a NanoVNA hardware version 2.0 being in the works and it could be ready as soon as January 2020.

  1. The nanoVNA [v2] will eventually reach 3GHz (and at a similar price to version 1).
  2. It's going to be based on the adf4350 + si5351.
  3. The 3 mixers are replaced with one higher spec mixer (ad8342) that is switched between the 3 channels.
  4. A variable gain amplifier is added at baseband using one opamp and switched feedback resistors for improved dynamic range.
  5. The Audio codec is removed and the stm32 built in ADC is used instead.
  6. The performance should be comparable or better to V1.
  7. Info about the baseband VGA design: A RFIC switch is used to switch the shunt resistor in the feedback path. The switch is basically "transparent" because the off state capacitance is in the femtofarad range (it is an RF switch) which is negligible at the IF frequency. The on state resistance is small compared to the resistors being switched in. Since the amplifier gain is mainly dictated by the feedback network, and the switch is "transparent", there is nothing other than the tempco of the physical resistors that can cause a temperature dependence. The RFIC used is the same as for the receiver RF switch, and it turns out all the maxscend switches do not have the shunt diode problem (most RF switch ICs have parasitic diodes from RF input to ground which will start to conduct at lower frequencies), so it has no theoretical lower frequency limit and can be applied at the IF frequency. This is a big improvement over using normal analog switch ICs which have capacitance in the pF range.
  8. Info about linearity: The code will perform a calibration of each VGA step on boot up. Since there is no temperature dependence the calibration only needs to happen once.

The layout designer has also posted, noting that the price will remain the same (roughly $50), but there will be several improvements including a wider frequency range, better dynamic range, and an improved PC interface.

Hi, NanoVNA V2 layout designer here. Here is what I know:

  •  V2 won't have a bigger display because it is too expensive
  • frequency range will go to at least 3.5GHz; PLL limit is 4.4GHz.
  • ADF4350 is used because of cost reasons; ADF4351 is more expensive by a factor of 5.
  • The layout is already fairly packed, so modular is not possible without a huge form factor.
  • Layout and shielding are much improved for higher dynamic range.
  • Price will be around the same as the existing NanoVNA. The design is already cost limited, so we can not do anything that will further add cost.
  • PC interface will be completely reworked. A binary protocol will be used similar to the xaVNA (we are going for full compatibility with the xaVNA PC software). If you are writing custom PC software for the Nano, please make sure the USB interfacing part is well abstracted away and easy to change.

The development timeline is going to be pretty long (by Chinese standards at least). We will iterate on PCB layout to get the best dynamic range. I think we might see initial (quantity limited) sales in ~3 months.

The NanoVNA Version 1.0
The NanoVNA Version 1.0

Just as a footnote, we received several emails from readers who wanted to make sure we note the credit edy555 should get. Originally edy555 had planned to produce his own units, but due to a Chinese ham enthusiast who had good intentions the design became popular and was soon cloned. We note that the NanoVNA v2.0 does not appear to be affiliated with edy555.

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