W8EMV - Whiskey Eight Echo Mike Victor

W8EMV call sign issued

I navigated the FCC dance successfully and now have call sign W8EMV, replacing the previous call sign KD8OQG. There's no charge for a "vanity" license any more, just a matter of filling out the simple online forms and waiting 2 business weeks.

I've had the emv login for many years, starting in 1985 with umix!emv and proceeding through emv@umich.edu, emv@ox.com, emv@msen.com, emv@cic.net, emv@coast.net, and now emv@monkey.org. So W8EMV is easy enough to remember.

I've updated my links on this site and changed the blog name. That will inevitably break a few things, and I am not aware of how to set up Typepad to transparently redirect an old name to a new one.

thanks and 73

Ed W8EMV

recordings of the BBC from the WebSDR at U Twente

Here's a few clips on Soundcloud from the BBC.

BBC World Service news on 7 January 2021, a minute from a shortwave broadcast with news from Washington DC. The broadcast is from 5945 KHz, a service to Asia.

BBC Radio 4 on 8 January 2021, three minutes from a longwave broadcast with an interview of Mary Trump. The broadcast is from 198 KHz, the longwave domestic service of Radio 4.

Both monitored at the U Twente WebSDR which has a handy "record" button.

A reminder to set your password on your MMDVM hotspot

My DMR hotspot was silent for some time because I had neglected to update it with a newly required password.

The Brandmeister network article on hotspot security has the detail that you need to carry this out. You'll want the "hotspot security" section of the "SelfCare" setting at Brandmeister, and on the MMDVM side the menu option is under "Configuration" / "Hotspot Security".

It took but a moment and now all is well again.

Listening to DMR on OpenWebRX

My notes such as they are say that I had OpenWebRX running last year around this time, but the 2019 experience was not accompanied by blogging and I have forgotten what I learned.

This year's install was very simple, using the Debian install instructions and then systemd to start and stop and reload the system.

The 2020 OpenWebRX setup has a lot more digital modes supported, and I was able to successfully decode a transmission from Ralph AA8RK this morning. I was listening on 443.5 (the output frequency of the W8RP DMR repeater) with my setup, which includes a Nooelec RTL-SDR tuner and a 8 GB Raspberry Pi 4. Miraculously, the DMR decoder picked up not just Ralph's voice but also decoded his call sign and channel number.

One funny thing about this repeater setup is that from time to time it will send out a short burst of traffic that OpenWebRX can't decode, see below for that.

Monitoring local 2 meter and 70 cm repeaters with a Realistic Pro-34 scanner

The Reuse Center used to be a warehouse full of reclaimed castoffs, a mish-mosh of home improvement items, old golf clubs, unloved books and music, and the very rare bit of electronics. Everything was priced to move, and we're sad that it's gone, having closed due to the current peculiar situation.

The rare bit of electronics I scored one weekend at this place is a Realistic Pro-34 scanner. This is a handheld device with 200 scanner channels in 10 banks, which was a $329.95 product at Radio Shack in the late 1980s. I found it for $2, and managed to source a compatible power supply for it for another $15 from T-Power (via Amazon).

Back in its day, lots of people did mods to the Pro-34 to add or cut a diode that affects coverage of certain prohibited bands. One such modification is accompanied by this direction upon completion:

"LASTLY, Now that you have made the mods, you can use the warranty card to light the Bar-B-Q Grill with."

The March 1989 edition of Popular Communications ("Pop Com") has a review of this scanner, and instructions on modifications. Look starting on page 25.

I have most of the frequencies you can see from the Washtenaw County piece of the W8SRC repeater guide programmed in, plus a few simplex channels. With the scanner turned on most of the time, I hear a few more things that I would if I only tuned in the radio when I was actively transmitting. Mostly though the local traffic is scheduled nets in the evenings, automated repeater announcements of the time of day on the hour or thereabouts, and every once in a while someone announcing when they are going mobile.

More details about the Realistic Pro-34 scanner on Rig Reference including a full user manual.

Tuning an MMDVM hotspot to minimize BER for multiple radios

My RD-5R gives about 0.4% BER when talking to my MMDVM hotspot, but my GD-77 with the same configuration gives nearly 1.0% BER. Audio quality is still good, but of course it's worthwhile to tune things to minimum error rates regardless.

Some notes on tuning the TX level on the radio:

• N6AMD, How to tune your MMDVM repeater with an SDR for low BER. Focuses on getting your audio levels correct; "If the raw audio is either too quiet or too loud, subscriber radios will not decode the digital signal properly." Uses pistar-mmdvmcal and an SDR to calibrate audio levels (TXlevel).

• F5UII, Install MMDVMHost on Raspberry Pi and tuning MMDVM for DMR digital mode . N6AMD's article is derived from this one, which uses both SDR and oscilloscopes for tuning. "The goal is simply that the audio levels are not too strong and do not saturate the analog input of the arduino".

Some notes on tuning the RX offset on the hotspot

• Ailunce, How to set RX TX offset. "Also every DMR radios may get a different BER when using the same hotspot. If you can't find a good balance for the BER between the different modes, it may be better to use different hotspots for each different mode."

Thanks to Christopher M0YNG on Feditalk to help me with some tuning ideas.

2020 software defined baseball season

Previously: 2019 and 2018.

The goal is to enjoy as much of the pandemic-shortened 2020 baseball season as I can via listening to far-away AM stations through SDR receivers.

I'm continuing to use the baseball section of my commonplace book to keep track of who's broadcasting where, and where you can listen to KiwiSDR or WebSDR receivers to tune in those broadcasts.

Two big changes in my listening since last year.

For East Coast stations, I'm more and more relying on listening through the WebSDR at K3FEF in Northeast Pennsylvania. WebSDR's can readily handle 50 or more simultaneous listeners, so there's less chance of congestion. This particular listening post will pick up stations from Connecticut to Washington DC.

In the KiwiSDR world, there are more and more Kiwi's that are using advanced technology to squeeze out more listening channels than the typical 4 channel setup. N6GN in Fort Collins runs a Beaglebone AI KiwiSDR setup that offers 14 simultaneous users. The usual tradeoff is that you get less of a spectrum waterfall display and more audio channels.

Some teams are easier to follow than others. I don't have a good way to copy Padres games, except via their Spanish language station. Phillies daytime games can be picked up via a station in Scranton, but 2000 watt WEJL drops down to 32 watts at night, not much of a powerhouse. Receivers do wink in and out from time to time, so any given listening suggestion is not a guarantee.

It's weird to listen to games, knowing that the crowd noise is synthetic, and knowing that some teams like the Marlins have had a piece of their season wiped out due to COVID-19. But it's still baseball - a weird, slightly mutant baseball, with seven inning doubleheader games and men on base to start extra innings.

New radio notes: Radioddity GD-77

I got two new Radioddity GD-77 radios the other day - one for new ham KE8PFB, and one for myself.

Programming the radio from the keypad is awkward but not impossible, and we got one analog channel up and running to reach the ARROW repeater. That was plenty to confirm that it was working.

We'll tackle DMR next. I have a DMR hotspot, so it should be possible to share it.

The included instructions were in German and in English, and the "how to get a DMR ID" instructions were for Europe. This led to a support ticket - the USA instructions are at RadioID.net.

The GD-77 is supported by dmrconfig, and I was able to convert my RD-5R configuration to it without too much trouble. The GD-77 only has two squelch settings, so the RD-5R's configuration needs to be edited - other than that, surprisingly easy.

The GD-77 user interface is nearly identical to the RD-5R. A few of the key bindings are a little different, but it's otherwise effectively the same radio as far as capabilities and controls. I guess that's OK, but I sort of wanted to get a completely different rig from what I already had. The tradeoff of course is that it was completely familiar.

Operating notes: new net protocol for Washtenaw ARPSC net

Our ARPSC (Skywarn) net switched to a new check-in protocol on the Sunday night net. Rather than giving your entire info all in one go, you check in with just a call sign, and then net control calls a roster.

This makes the net more of a directed net, and spends less time on calls that double. It also means that net control has more than one opportunity to correct a missed call sign.

Never one to miss an opportunity to innovate, I'm going to try this approach on a big zoom call, one where it's always uncertain who goes next.

See https://mastodon.radio/@w8emv/104703215788181316 for discussion.

Fine business! Moving to Twitter handle @W8EMV

I'm switching around my Twitter setup so that my main account is now @W8EMV. The goal is for everything in that stream to be on topic, with two acceptable topics of radio (ham radio, shortwave and AM DX listening, SDRs, whatever) and work (open source ecosystem development at Packet, an Equinix company).

With any luck the narrowing of focus will result in a more manageable stream. Every post should include the word "radio" or "open source" in some measure, or reference the same.

My old account still exists but it's protected. As the Green Bay Packers once said, "Fresh Start with Bart". It was too much work to even comprehend how to deal with 60,000+ tweets.

Twitter is problematic for many reasons, so I'm trying to only reopen a narrow channel to it.

What is the effective coverage of my DMR hotspot?

My new MMDVM DMR hotspot shipped with a little SMA antenna, and has a power output measured in milliwatts. I wanted to figure out just what kind of effective range I had for it, so that I could get away from my desk while connected to it.

My radio is a DM-5R with low power at 1 watt and high power at 5 watts. At about a block away from home, transmitting on low power, I can get a clear echo reply to my hotspot with Parrot. At four blocks away, the low power TX doesn't get into the hotspot, but my RD-5R still picks up some fraction of activity on an active channel.

The next test was to change to high power (5 watts) on the radio, and to get a better antenna setup for the hotspot. I have a 2 meter ladder line antenna that also works on 440, so I connected that up to the SMA port to see how it would work. My best distance was about 137 meters, as measured by GPS, from my house to the bus stop. That's almost line of sight with just one building in the way using high power (5 watts) on the RD-5R into the hotspot, and Parrot to verify transmissions.

Some other DMR range experiments from Youtube:

• K0LWC measured 0.7 miles (1100 meters) with an Anytone 878 into a 10 milliwatt hotspot, with clear line of sight across a park and no buildings obstructing his view.
• KG4VDZ hooked up a SharkRF OpenSpot 20 milliwatt hotspot to a 50 watt amplifier, and claims a DMR range of 15 miles using a vertical antenna on top of a tower.