Some station letters of RRI, 28 Oct 2012

Way too weak.

My noise floor is -110 dBm in the 6 MHz band, with the fridge off. Pretty disappointing. The SNR hit at the end was due to an AM carrier at 6030 kHz.

The Disco Palace DRM @ 17875 kHz, 27 Oct 2012

They came back some time last week. Yesterday, there were problems, and today it was silent.

First observation: RF energy outside the band is not well controlled.

Well this waterfall looks awfully familiar.

A 64-QAM constellation is being seen in what should be the 16-QAM SDC. Probably an encoding issue is causing the decoder to lose frame sync and pick the wrong time to start SDC decode.

The issue went away until 20:20 UTC, and remained that way for the rest of the broadcast.

BC-348-Q vs iPhone

An AM radio does not "connect" to a radio station.

A radio station is not a wireless network. Wireless networks have uplink and downlink channels. A radio station only has broadcast, therefore it is a broadcast network.

A BC-348 needs an external antenna and 24 V DC to receive (not connect) a signal 9800 miles away and subject to fading and doppler.

An iPhone uses it internal antenna to connect to a nearby Wi-Fi network, pulls the Radio Australia stream from a server 9800 miles away via the internet, and outputs the audio through its speakers. It requires 3.7 V DC.

An iPhone also displays colour graphics. Try that with a BC-348.

Voice of Nigeria DRM @ 15120 kHz, 8 Oct 2012

The fading profile was unusual.

Fairly uniform fading, and slow.

I used to think that this interference was caused by the air conditioner, but it's autumn now. But the other day I think I figured out what it really was: the fridge.

Unusually low doppler. This lasted until 19:15 UTC, when "regular" fading and doppler returned, along with a commensurate loss in SNR.

Stop trying to shoehorn DRM into everything under the sun

Since Disco Palace is once again absent from the airwaves, here is another totally unhelpful collection of words.

How did mediumwave AM for emergencies lead to DRM providing a smartphone experience? Drugs: just say no to them. For one, you don't need to be connected to the internet to use a smartphone (i.e. playing games). For another, the whole social aspect of certain apps is incompatible with the unidirectional nature of broadcasting.

But confusion over whether DRM delivers cute kitten videos and tweets in an emergency aside, let's look at the current infrastructure that provides said smartphone experience, in a country with reasonably current wireless service.

If I've got a smartphone, I want to see at least 3G speeds. As a baseline, that means HSDPA. At the most pessimistic channel profile, I can expect 1.2 Mbps downstream with a 5 MHz channel.

Now what might I expect out of DRM with a 20 kHz channel? If I assume that I have a great channel, high SNR, and puncture the hell out of my convolutional code, I get...

72 kbps

That's what, like two dial-up modems? And bear in mind that reality says there will be loss, so unless you want to piss off your audience, you'll have to periodically re-broadcast data, a la Teletext. And at that data rate, text might be all you can realistically expect to broadcast.

(The entire AM band in America, from 540 kHz to 1710 kHz, is 1.17 MHz wide. Just saying.)

But let's assume that you magically have data in your radio. Now what? Well you have to process it and display it, don't you? Wait, isn't that what a smartphone does too? Are you really going to beat a smartphone on power consumption when you're doing exactly what a smartphone does?

Here's where Nigel Holmes' GE Super Radio remark collides with addressing DRM "power issues" to create a hypothetical pocket-sized, multimedia capable receiver. You see, I followed the Super Radio link and ended up at the first generation Super Radio manual. Here's what I noticed:

It is definitely not pocket-sized, because it takes 6 D-Cell batteries. Forget power consumption for a moment, and check how much capacity a D-Cell has: 2000 mAh on the low end for Ni-Cd.

What is the capacity of the battery in the Samsung Galaxy S3? 2100 mAh. So at worst, your humble analog radio has at least 5 smartphones worth of battery, in all likelihood 5 times that for alkaline, and it doesn't have to do all the things that a smartphone has to do like, I don't know, multimedia things.

I don't know what expectations one ought to have concerning battery life, but a digital receiver the size of a smartphone cannot hope to outlast a D-Cell powered analog radio, even if it only has one battery. An analog radio doesn't have an entire digital receive chain, or a baseband processor, or a CPU/GPU SOC, or a DAC, because it's analog.

And lastly, a bog standard MW receiver doesn't need high sensitivity. Any MW broadcaster who cares will ensure copious SNR at all times throughout their coverage area. If you think you're going to DX punctured 64-QAM, just say no to drugs.

A non-attempt to contact The Disco Palace

Via e-mail:

Delivery to the following recipient failed permanently:

     info@thediscopalace.com

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 Requested action not taken: mailbox unavailable or not local (state 13).

Via their feedback form:

Warning: mail() [function.mail]: SMTP server response: 550 Requested action not taken: mailbox unavailable or not local in C:\Inetpub\vhosts\alyx-yeyi.com\thediscopalace.com\contact_sendmail.php on line 38

Warning: Cannot modify header information - headers already sent by (output started at C:\Inetpub\vhosts\alyx-yeyi.com\thediscopalace.com\contact_sendmail.php:38) in C:\Inetpub\vhosts\alyx-yeyi.com\thediscopalace.com\contact_sendmail.php on line 45

I'm too lazy to sign up for twitter or FB just to ask them what's going on.

CRI talks Gangnam Style @ 6020 kHz, 6 Oct 2012

I swear, I just happened to be there when it started. Totally not worth the 25 minute slot, though.

• It is hilarious that they mention YouTube stats. Last time I checked, YouTube was banned in China. They probably watched it on Youku.
• "Heeeyyy sexy lady" is not the only English phrase. "You know what I'm sayin'?" is said just before the last chorus.
• Much time was wasted dismissing and/or not dismissing the song and/or video. If boiling the yuppie-hipster-douchebag-trustfund baby demographic down to a horse-riding dance is nothing, then haters are just gonna have to hate.
• There was a head-scratcher about coffee and American companies invading. No, Starbucks is a status symbol (in Asia) and hipster-douchebags drink it in public to show off.
• If you really wanted to know why Gangnam Style took off, Google (which is banned in China except HK) and Wikipedia (also banned in China) aren't bad places to start. On a totally unrelated note, Blogger is banned in China.
• That female guest should totally be the host. She sounds like she spent a good chunk of time in America, which is what this segment seems to want to project.

On another totally unrelated note, I once heard a CRI news anchor pronounce Mary J. Blige's last name as "Bleej." Clearly it wasn't the British anchor on the Beijing Hour.

The Mighty KBC @ 9400 kHz, 7 Oct 2012

I maybe heard a Beach Boy's song. 35 dB carrier to noise isn't going to cut it, unfortunately. Also, this -95 dBm noise floor is why I'm loathe to venture into the 9 MHz band. I may check again later.

The Disco Palace DRM @ 17875 kHz, 6 Oct 2012

This is the second day in a row (that I know of) where the transmitter has been down.

Oh hey, Voice of Nigeria DRM has no audio feed

Or rather, has no voice.

One might think that there should be at least one quality monitoring station to report this kind of thing so it would be fixed. Or maybe they do, and the conversation went something like

"This audio quality is an embarrassment to the country! Turn it off!"

Flash update: the audio stream came back at 19:41 UTC and it's broadcasting... noise. That's right, white noise, the kind with a flat power spectral density.

If I wanted 3 kHz of noise, I could just use upper sideband on an unoccupied slice of spectrum. On the other hand, this isn't as irritating as their sorry attempt at broadcast quality audio.

BBC World Service DRM @ 7355 kHz, 6 Oct 2012

-80 dBm subcarriers right now vs -85 dBm subcarriers last week. Solid, but no content in Journaline.