Category Archives: Digital Modes

Alexander reviews the Avion AV-DR-1410 DRM receiver

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Many thanks to SWLing Post contributor, Alexander (DL4NO), for the following review of the new Avion DRM receiver:

A review of the Avion DRM receiver

by Alexander von Obert (DL4NO)

The Avion AV-DR-1401 DRM receiver has appeared on the SWLing Post before in a previous review.

Amazon India does not sell the Avion outside of India. As it happens, I found someone who was willing to buy it for me and bring it with him from India to Germany.

The first impressions were quite disappointing. This feels more like a prototype, not a polished product:

  • The power supply produces lots of interference and runs quite hot. Unless I find another power supply, I can either charge the battery or listen to the radio.
  • The handle rattles. Such things often are symptoms for the whole product.
  • The firmware fails in many ways: update errors of the display, very confusing user interface.
  • No acceptable field strength indicator, especially in DRM until a signal is decoded. If you have a selective antenna you need to switch to AM to tune it. And then you tune it by ear or by numbers. No bar of any kind.
Avion AV-DR-1410 DRM

Radio Romania

Radio Romania produced very good signals this evening in southern Germany on 41m. But with the built-in antenna, DRM reception was impossible even in my shack directly under the roof. A Degen 31MS selective active antenna indoors enabled sketchy reception of Radio Romania and All India Radio on 41m. Reasonable reception was only possible with my external antenna.

All India Radio

All India Radio

Just imagine why I took the trouble to get the receiver! It is a far cry from what I really wanted: a modern replacement of my trusty Sony ICF7600D from the 1980s. I had to retire it for mechanical reasons after it travelled with me for 20 years.

In India, they might not have the industrial infrastructure they have in China or Japan, but an intensive firmware update is urgently needed. Software is something they are good at in India. Many problems could be solved that way:

  • The volume knob has no stop and must be pressed for a few seconds to turn the radio on or off. A short press could be used to switch it between volume and tuning.
  • A reasonable field strength indicator should be introduced.
  • The remote control does not work reliably.
  • With the “mode” switch I can select AM, FM, or DRM. But I have not found anything that the “band” switch could be doing.
  • The “scan” switch works on FM and puts all transmitters found into the favorites. But neither is that the function I would expect it to do nor does it work on other bands.

From my preliminary tests I fear the unit has massive large-signal problems. For example, I heard distorted signals of Radio Romania on bands where they were not transmitting at all. I use an active antenna but this is the same I use for the DX Patrol or SDRplay RSP, therefore I know that my antenna is not to blame. I also see this as an indicator about the DRM signal of Radio Romania.

I could not help but open the Avion receiver: [the internal antenna worked so poorly, I wanted to investigate].

I must say that the rattling handle was an accurate indicator of production quality.

Inside the Avion

Inside the Avion

See “Inside the Avion” image above (click to enlarge). The back side on the left was originally covered by an aluminum shield. I had to remove it as the wires are quite short–one cannot put the two parts flat on the bench otherwise. You see that they tried to improve the shielding on the right.

AVION internal antenna preamp

Avion internal antenna preamp

See “Avion internal antenna preamp” above (click to enlarge). The circuit board at the lower left corner of the first picture is the preamp for the internal antennas. In the lower left corner is the telescopic antenna connection. The wire here was extremely short–either it broke before and made contact by chance or I broke it when I dismounted the circuit board. At least I did not force it (still a bad manufacturing practice).

If you examine the circuitry, you see very bad practices: C2 directly connects the antenna to the base of Q2. It must be a bipolar transistor considering R3/R4. At least there is DN1 which seems to be protection diodes. On the whole board I can find no inductivities at all. There is absolutely no band limiting.

AVION broken shilding wire

Avion broken shilding wire

See “Avion broken shielding wire” above. The shielding wire had broken from the soldering. That was definitely not my fault. At the yellow isolation, a second wire is connected. That is the wire routed around the backside without any connection. This doesn’t make sense to me.

Avion crushed battery holder

Avion crushed battery holder

See “Avion crushed battery holder” above. The battery holder is fixed together with the aluminum shielding. The worker crushed the lug of the battery holder while mounting the shield. A few other threads were torn, too. A typical case of too much strength.

Avion seems to know about the inherent RFI problems of this receiver, but could not solve them. No wonder I have to use an external antenna.

Perhaps I will replace the antenna preamp with something reasonable.

Otherwise this radio will gather dust here.

Thank you for your report, Alexander–I’m sorry to hear about your experiences with the Avion, especially after the trouble you went to obtaining it.

So far, I’ve heard no truly positive reviews of the Avion AV-DR-1410. Sadly, it sounds like a radio to avoid.

How Bob McGwier used a Cray-2 supercomputer to decode a ham radio transmission heard in Star Trek IV

Startrek4-MoviePoster-SmallIn response to our recent post with a message to us from Star Wars sound designer Ben Burtt, SWLing Post reader, David Guilbeault, comments:

Here’s a similar story that circulated on the Internet around 1990 (pre WEB!). I worked in packet switching at that time and was very impressed with Bob’s achievement (even with a CRAY to work with) .

I reached out to Bob McGwier (N4HY), who is a Facebook friend, and he has kindly given us permission to share his message again here and with a few new comments:


Star-Trek-IV-Cap

Decoding HF packets in Star Trek IV

Originally posted on December 4, 1989 by Bob McGwier (N4HY)

Several months ago, Harold Price, NK6K, challenged me to demodulate what he thought might be HF packets in Star Trek IV.

Chekov-Uhura-Star-Trek-IV

During the scenes where Scotty is valiantly trying to beam both Chekov and Uhura back from the U.S.S. Enterprise, where they have been stealing Nuclear vessel high speed photons, Scotty is having a hard time hearing them.

Scotty-Star-Trek IV

Listen to the audio clip by clicking here or using the embedded player below (target sound is at 5 seconds):

One of the sources of interference is what appeared to Harold to be HF packet. Always being one to rise to a challenge, I took on the job of doing some fancy Digital Signal Processing footwork. Almost from the first I was certain that it must be an HF packet since my very first demodulator attempt clearly revealed flags before the start of a frame and end of frame was also clear. I knew it was HDLC of some variety.

Several things impeded the effort, including Scotty’s voice on top of the packets, some SSB from 20 meters was also nearly on top of the signal. All of this had to be filtered out. I spent an hour of time on the Cray-2 at work and used the fanciest FSK demodulator I could write and I finally had noisy baseband signal plotted on paper in front of me. I did my best to get an integral number of samples per baud as the signal was very noisy, and though the bits could be made out by eye, I could tell that it was going to take another hour of Cray-2 time to get the clock recovered and to make good bit decisions. In a couple of places, HDLC showed me what were clearly bit errors, and these could be done by eye as well.

A Cray-2 operated by NASA. (Source: NASA)

After the filtering, and building a demodulator for the badly mis-tuned signal (almost 900 Hz below), I took the bits to Phil Karn, KA9Q and he decoded the NRZI data and proved beyond a shadow of a doubt that it was indeed an HF amateur radio packet. It was WA8ZCN-0 sending an RR for NR-3 to N6AEZ on 20 meters. I got Bill Harrigill, WA8ZCN on the phone and he agrees that it was probably him.

Thanks Harold for the challenge and Phil for the help.

Bob N4HY

P.S. A Cray-2 is about 50% faster than the fastest Pentium-Pro computer available today.

Again, keep in mind that the message above dates from 1989! This past week, Bob added the following comment when I contacted him:

The Cray Supercomputer on which the work was done was being operated on behalf of the National Security Agency by my research institute.

I received permission to “to test optimal algorithms for software decoding of FSK transmissions” and this was my test case!!!!

That is why Phil Karn was decoding the AX.25 bits by hand. I did not have permission to develop link layer protocol code, though I tried.

A few years later when half the bad guys in the world seemed to be using AX.25 and cheap ham gear I said “See, I told you so several years ago and you didn’t listen”.

I used that transmission in so many different ways I no longer remember them all.

That’s fantastic, Bob, and so great to know the back story on your decoding process! Thank you again for sharing this with us!

Star Trek fans can find the scene Bob references starting around time mark 1:12 in the film.

A review of the new Avion receiver and a few thoughts about DRM

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Many thanks to SWLing Post reader, Mike Barraclough, for sharing a link to this review of the new Avion DRM receiver by DRM Radio Forum user PhilipOneL. I’ve pasted his evaluation of the Avion below–you can read this, along with the full discussion thread, on the DRM Radio Forum:

I received my Avion AV-DR-1401 this afternoon and have had it up and running for a couple of hours. There is no instruction booklet with it so I am puzzling over the 41-button remote. It is not as user-friendly as I hoped.

First impression: somewhat cheap feel to it. I have put a small bend already in the thin but long aerial. But that is just the outside (handle, volume control, master power switch, and aerial); I hope it works well anyway. But that cheapness hurts when the price of the radio was fairly high to begin with and I paid more than I wanted for a private company to ship it (Fedex).

The radio arrived with its battery fully charged: nice. (But I need to get an adaptor for the AC adaptor’s mains plug which has tubular prongs rather than the North American blade prongs.) I like a lot the fact that it runs normally with its internal battery rather than plugged into mains. This means I can carry it away from noise sources. And it is very carryable — it reminds me of a small 1965-era beach radio in size.

Turned on, it scanned the local FM spectrum well and registered all the local stations. But I cannot get the Scan function to operate on MW and SW, nor in DRM mode. With an outside antenna (8 metre wire) attached, it was able to get the AIR DRM broadcast on 7550 kHz and decode it. It didn’t seem to be able to get enough signal with just the extending aerial.

I have not figured out yet how to make it register a medium-wave, shortwave, or DRM station in its memory; it does not happen when the button labelled “Delete / Store” is pushed. Among the 41 buttons, there is no other likely candidate for that function.

Shortwave sensitivity in AM mode seems to be poor. I was listening, for instance, to ERT Greece on 9420 on the three receivers now on my desk: Satellit 750, MorphyRichards 27024, and the Avion DR-1401, each in turn connected to the same outdoor antenna. The MR27024 produces the best sound and greatest s/n ratio. It seems far more sensitive than the Avion. But who knows? I may discover I am doing something wrong with the set.

Tuning can be done by inputting a frequency on the remote. Alternatively, the volume wheel can be pushed (this takes two hands) to convert it to a tuning knob. Two problems are apparent. One is that the signal is muted as you tune until you wait on a frequency for four or five seconds. Thus it is a slow and aggravating experience to try to tune across a band looking for signals. Secondly, as soon as a station is tuned and producing audio, the knob goes back to being a volume control. Grrrr. (I think there is a professor at all the design schools who seems to be telling all her/his students to be visually minimalist in design and to give every knob multiple functions. That professor should be publicly shamed until she/he recants and causes all the students to go back to multiple knobs each of which does one thing well.) When the radio gets itself ready to produce audio it seems to ramp itself up to full audio in a series of four steps, each a half-second or so after the last — it is an odd-sounding process. It is like a faulty AGC circuit; perhaps it is.

Sound quality is mediocre at best on AM (both mw and sw). I didn’t listen long enough to the DRM signal from AIR before it signed off to get a good idea of DRM audio quality; I was busy cooking supper. FM audio is mediocre too on the internal speakers but, piped out through the headphone jack to external speakers, it is quite good. When I piped the AM audio out it still seemed mediocre.

Why the AM sound is mediocre seems to be related to two things: the tiny speakers (about 8 cm or 3.3 inches) and the bandwidth at the radio stage. Even comparatively strong (and clean) signals like RHC on 6000 kHz have what may be adjacent signals mixing in — perhaps even internal mixing products? I heard a splash of a local FM station at one point while listening to a shortwave band.

I have written my contact at Avion (Ankit) asking for an instruction booklet, or a pdf of one. I hope I’ll get that early next week (if indeed they have one).

I hope over the next week I will get some chances to check out more DRM signals. I am also hoping that my gradual love affair with the MorphyRichards radio will be replicated here. When I first got the MR27024 I was very cranky about its weird ways of doing things. But once I got a good antenna on it, and got used to its ways, I prefer it to all my other radios as a table-top radio (that is, one useful for listening to specific regular stations). The MR’s radio-stage DSP is quite lovely and makes for good sound. I doubt the Avion will seduce me to quite the same extent, but it may grow on me in other ways.

I understand the problems with DRM but I am still a fan of of the system. I bought this Avion set partly in hopes that I would encourage the manufacturer in some small way. I will use it but I suspect that the minimalist design features (which were also a part of the MorphyRichards design) will turn off users of the Avion.

I’m not terribly surprised by this reviewer’s assessment. Just looking at some of the preliminary info on the Avion receiver last year made me think of previous DRM portables like the Newstar DR111 and the Uniwave Di-Wave 100.

The UniWave Di-Wave/Di-Wave 100.

The UniWave Di-Wave/Di-Wave 100.

I have a hunch all of these designs were fleshed out by engineers and entrepreneurs who had not gotten customer input in advance.

It’s sad, too. While I know DRM (via the shortwaves) was a “cart before the horse” innovation–meaning, broadcasters adopted the technology well before consumer receivers were on the market.

I really wish the medium would’ve gained traction.

While I prefer the rich sonic texture of amplitude modulation, I love listening to DRM broadcasts well. Last year, during my presentation at PARI, I played a recording of a piano concerto I heard on one of Radio New Zealand International’s DRM broadcasts. If memory serves, the audio clip was taken from this recording I made on June 21, 2104:

Through the presentation room’s hi-fi system, the music sounded absolutely brilliant.

To put what this audience was hearing in perspective, I told them:

“We’re listening to a radio station some 8,300 miles away without the use of the Internet, mobile phones, satellites, or any sort of subscription service. We’re hearing FM-quality audio, streamed wirelessly and originating from the other side of our planet.”

I then received a number of questions like: “How is this technology possible?” and “Do they make car radios that can receive these broadcasts?”

There’s magic in DRM. Sadly, I feel its deployment was awkward and its window of opportunity may have already passed. An affordable, effective, and simple DRM receiver (combined with serious, viral publicity) could turn the tide somewhat–but it doesn’t seem like this will happen anytime soon. Each new DRM portable is only a slightly improved iteration of its predecessor and the price tag continues to be too high for effective market penetration.

I want to be proven wrong, though.

VOA Radiogram 128 on a cheap Tesco shortwave radio

VOA-Radiogram

SWLing Post reader, Christopher, lives on the north coast of Labrador, Canada. He recently contacted me regarding the purchase of a new receiver–he’s currently stuck with a very inexpensive analog portable he purchased at the UK grocery store, Tesco: the Tesco RAD-108.

While the RAD-108 has poor sensitivity and selectivity, it’s still (evidently) more than capable of receiving the VOA Radiogram. Many thanks to Christopher for sharing this video he found on YouTube:

SPROUT SSTV and Digitalker Every Sunday

SPROUT SSTV and Digitalker active every Sunday

SPROUT SSTV and Digitalker Active Every Sunday – AMSAT-UK

AMSAT-UK Announces SSTV Activity Every Sunday

Slow Scan TV (SSTV) images in Scottie 1 format will be transmitted from the SPROUT satellite every Sunday (Japanese Standard Time) on 437.600 MHz FM (+/- 9 kHz Doppler shift). The Digitalker will also be active.

SPROUT, a 20 x 20 x 22 cm amateur radio nano-satellite with a mass of 7.1 kg, launched successfully with the L-band (1236.5 MHz/1257.5 MHz/1278.5 MHz) Synthetic Aperture Radar (SAR) satellite ALOS-2 on May 24, 2014 at 0305 UT. SPROUT is in a 654 km, 97.9 degree inclination Sun Synchronous Orbit (SSO).

SPROUT (Space Research On Unique Technology) was built by students from Nihon University

— A FM Digitalker will enable the satellite to speak to amateurs around the world.

— The Voice Message Box will record transmissions from radio amateurs and play them back.

— Pre-loaded images from the Message Gallery can be transmitted using Slow Scan TV (SSTV).

— Pictures of the Earth can be transmitted by SSTV and radio amateurs can receive it using free software such as MMSSTV. As part of the Earth mapping project the team ask radio amateurs to contribute pictures they have received from the satellite for display on the SPROUT website.

Callsign: JQ1ZJQ

Size: 214x210x220 mm

Weight: 7.1 kg

Mode: 1200bps AFSK, 9600bps GMSK

CW downlink 437.525 MHz

FM packet downlink 437.525 MHz

Digipeater uplink 437.600 MHz

Digitalker downlink 437.600 MHz

SSTV downlink 437.600 MHz

Many FM radios can be switched been wide and narrow deviation FM filters. For best results you should select the wider filter designed for 5 kHz deviation FM.

— SPROUT English website http://sat.aero.cst.nihon-u.ac.jp/sprout-e/

— SPROUT Japanese website http://sat.aero.cst.nihon-u.ac.jp/sprout/

— Nihon-Univ. Miyazaki Laboratory on Facebook

https://www.facebook.com/pages/Nihon-Univ-Miyazaki-Laboratory/406566642818860

— Telemetry Software http://sat.aero.cst.nihon-u.ac.jp/sprout-e/2-Software-e.html

— Telemetry format http://sat.aero.cst.nihon-u.ac.jp/sprout-e/2-Formats%20of%20telemetry-e.html

SPROUT launch data page

http://sat.aero.cst.nihon-u.ac.jp/sprout-e/2-Launch%20data-e.htmlTLE’s from the North American Aerospace Defence Command (NORAD) are also available at http://celestrak.com/NORAD/elements/tle-new.txt

Free Slow Scan TV (SSTV) software MMSSTV http://hamsoft.ca/pages/mmsstv.php

The JE9PEL website has information on other satellites on this launch

http://www.ne.jp/asahi/hamradio/je9pel/jaxalos2.htm

(Full details and links may be found here.)

Robert Gulley, AK3Q, is the author of this post and a regular contributor to the SWLing Post. Robert also blogs at All Things Radio.

Avion DRM Receiver now shipping via Amazon India

Avion

The Avion portable DRM receiver is now available on Amazon India (click here to view). It’s being sold for 14,999.00 INR (roughly $230 US).

At time of posting, The Avion DRM receiver only has one review by someone who has (obviously) never used the radio. They give one star then state: “price is very high. so i hate this product.

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While I dismiss reviews like this, I must believe that this price is, indeed, high for most Indian consumers; especially when compared with alternate forms of media consumption (smart phones, analog radio, FTA satellite TV, etc.). It would be high for me, too.

I hope, at least, that the Avion performs well. I have no plans to review the Avion DRM receiver at this point simply because it’s challenging for me to find and decode DRM here in North America with my SDRs hooked up to large external antennas. Don’t get me wrong–occasionally, I do get amazing copy–but it’s typically when conditions are favorable. Listeners in Europe, Asia, and Oceana would have better results, no doubt.

Has anyone seen an objective review of the Avion DRM receiver? Please comment.

Click here to view the new Avion DRM receiver on Amazon.in.

Hearing Ghadir: Iran’s Sepehr Phased Radar System

Mehdi-Waterfall

In response to Andrea’s UVB-76 recording, SWLing Post contributor, Mehdi, comments:

Thomas, another signal which may sound mysterious:

Iran’s OTH Radar, named “Ghadir”; part of Iran’s Sepehr Phased Radar System.

They’d polluted the 10-meter band [in the past]; now they transmit on 26MHZ. (See spectrum in screen capture above.)

Sound: https://clyp.it/ldpxab2a

By the way, here’s my recording of UVB-76:
https://clyp.it/knvubeur

Many thanks for sharing those audio clips, Mehdi! Now I’ll know what Ghadir sounds like, should I hear it on the bands.