Thursday, December 13, 2007

DX Tuner Toplist

DX Tuners continues to grow as a no-fee, invitation only site. Several thousand user accounts have been issued, I understand. My Pennsylvania DX node, running on an Icom R-75, has been working well since I replaced my router. As seen in the about snapshot, it ranks #2 in total visits this week (Dec 13 2007).

Thursday, November 22, 2007

DX Tuners Returns

It's back! About 6 months after closing down the network, Kelly Lindman of Sweden brought the network back to life. Now run as a no-charge private network, many of the radios on the system are back again. Currently Kelly has capped the membership to the network, but expects to open it back up in the future.

My node, the Pennsylvania DX radio, is back - this time with an Icom R-75 receiver replacing the former IC-718 transceiver which I plan to use for ham radio purposes.

Welcome back!

Saturday, September 15, 2007

IBOC - Night 3

What a difference two days makes. This SDR-IQ plot shows the entire 695-865 kHz wide band filled with the tell-tale white bands of IBOC digital hash. Compare to my previous post which showed a relatively open spectrum the first night of IBOC, Sept. 14 2007.

Friday, September 14, 2007

Start of Nighttime IBOC

At 12:01 AM Eastern last night, full nighttime IBOC broadcasting began in the US on the medium wave band. Above is an example of the spectrum from the SDR-IQ receiver showing the digital hash from 700 WLW and 710 WOR extending to stations +/- 15 kHz from their carrier. On this band segment those two stations were by far the most notable IBOC signals. It's not certain whether any other stations were broadcasting on IBOC in that range last night.

Monday, July 9, 2007

Scheduled Recordings with Spectravue

I love using my new SDR-IQ radio to record 190 kHz of spectrum. But, the program that controls the radio (SpectraVue) only accommodates a single event recorder which can repeat once per day. I like to do repeated top-of-the-hour recordings during the night while I sleep (from, say :58 to :02) to review for IDs later in the day. Until the author of SpectraVue adds that capability, or others add the feature via a separate application, I needed another way to do it.

Once SpectraVue is running and configured to record, pressing the "start" (F12) key starts the recording and automatically saves the resultant data into a uniquely-named file. Pressing the "stop" (F10) key stops the recording. Each time you start the recording, it automatically creates a new data file with a date and time stamp. I hit upon the idea of using a macro program that sends key presses to the program to do this.

I found the free program AutoHotKey through a Google search. Using its built-in scripting language, you can send the commands to start, wait a programmable period of time, then send the command to stop. Here's the simple script I wrote and saved as a text file:

WinActivate SpectraVue 2.21
WinWaitActive SpectraVue 2.21
Send {F12}
Sleep, 240000
Send {F10}

As you might guess, the first two lines make sure the SpectraVue program is active, the next line sends the F12 command to start, the program waits 240,000 milliseconds (4 minutes) then sends the F10 command to stop. Now all that's needed is to run the macro script on a schedule.

To create a scheduled event in Windows XP, go to the Control Panel and click "Scheduled Tasks." Double click "Add Scheduled Task" then browse to the AutoHotKey script file you created. Specify the start time, and make it a daily event. AutoHotKey will run with that script every time it's scheduled, and send the keystrokes to SpectraVue. Once the event is created, right click the event in the Scheduled Task window, click "Properties", then click on the Schedule tab then "Advanced". This lets you repeat the scheduled event every hour throughout the night.

This process provides an hourly schedule execution for SpectraVue recordings, and lets you enjoy nighttime top-of-the-hour ID chasing during the saner hours of daylight!

Monday, June 18, 2007

SDR-IQ Image Reception

I received the SDR-IQ over three weeks ago and have been having a lot of fun with it. The ability to visualize the spectrum really changes the way I listen to the radio.

One thing I noticed, though, is that my two local AM stations (1 kW @
1 mile, 5 kW at 3 miles) both show up as "images" at +/- 196 kHz from the fundamental frequencies. These images are down about 60 db, but that puts them at about the same signal level (-90 to -100 db) as most of the other stations I can pick up.

I posted a message to the SDR-IQ group on Yahoo but haven't heard from anyone else whether my experience is unique. More on this if I uncover anything new.

Sunday, June 17, 2007

The Look of IBOC

Several stations seem to be broadcasting IBOC at 8:30-9:00 pm local (EDT) on June 14, as seen in the above graphic of the band from Spectravue as captured on my SDR-IQ.

The image shows 2 IBOC noise bands, one on either side of 760 WJR's carrier. As you can see, 760 itself is clean, but on the "far sides" of 750 and 770 carriers (e.g. lower sideband on 750 and upper on 770) the audio is "white" with a noise band 5 kHz wide. You can also see the same effect, albeit not as strong, around 840 (WHAS?).

What is slightly encouraging is that the sideband opposite the noise (e.g. lower SB on 770, upper SB on 750) are not as polluted by the IBOC noise; they are actually listenable despite the their other sideband being wiped out. The other thing I see is that the noise bands fade in and out at different levels from each other (sometimes only one is visible). Not sure why that is.

Anyway, this is what we will be looking at in the very near future on the US medium wave band.

Saturday, May 26, 2007

SDR-IQ Day 2 Experiences

OK, I figured out what I was doing wrong when I play back recorded SDR-IQ RF files in Spectravue... you need to explicitely tell the program what frequency the recording was centered on when playing back. If the "Center Frequency" in the spectrum was 620 kHz, then you need to tell the program that on playback. I also noticed that, for some reason, the "Invert Spectrum" option was defaulted 'on' every time, so the frequency of the stations in the 190 kHz of displayed spectrum were inverted (e.g. if I was centered on 970 kHz, the next higher station would be 960 rather than the expected 980 kHz). Once you play with Spectravue for an hour or two, everything makes perfect sense.

I did several top of the hour recordings to see exactly how this all works. It was great fun to be able to go back and listen to the TOH IDs of 19 different AM stations as many times as I wanted, and adjust the bandwidth and mode (AM/USB/LSB) for each one. I fired up Total Recorder, and by picking the "software" audio input was able to record each of the stations' audio, as I listened, to an MP3 file.

I noticed some interference-like stuttering in the audio at various times, which seems to go away when I cut the spectrum down to 150 or 100 kHz from 190 kHz. I am using a 4-year old 1.8 GHz Dell desktop, and I am presuming that I might be taxing the processor/bus a little too much at the high setting.

(Update 6/17/07 - I moved over to a newer Compaq 3100+ Sempron machine and there are now no stuttering or gliches)

I'm happy with the SDR-IQ!

To learn more about the SDR line of radios, join the Yahoo Groups SDR-IQ or SDR-14

Friday, May 25, 2007

New SDR-IQ has Arrived!

(5/25/2007) I just received my new SDR-IQ software-defined radio from Universal Radio - it seems like they got a small shipment in, and I had been monitoring their website for the announcement. The version I purchased was just the bare board, not the complete unit mounted in a case (those seemingly are still waiting for FCC approval). Cost was $399, quite reasonable considering its capabilities.

The current link to the radio on their web site is: SDR-IQ

[UPDATE 5-26-2007: Universal announced they are sold out of the boards, and would have more later]

[UPDATE 9-7-2007: The Universal site no longer lists the bare board version anymore, but appears to have the complete SDR-IQ with case available on their web site]

I will be writing more about the SDR-IQ in the future, but was very impressed by its operation the few minutes I spent with it tonight. Most exciting is the ability to see the spectrum across 190 kHz of bandwidth in real-time, and the ability to record that spectrum to hard disk for later listening (as if it were live). I had a small glitch with the included Spectravue software on playback of an RF recording, as the frequencies of spectrum displayed were different from what I had recorded. But, I presume this is due to "pilot error" on my part, and I will work more with it in the coming days to see how it all works.

Friday, April 27, 2007

DX Tuners, RIP

This past week I received a sad email from Kelly Lindman, founder of DX Tuners (formerly know as Javaradio) in Sweden:

Dear DX Tuner Site Operator.

As you may be aware I founded and have operated DX Tuners with various people’s assistance for over 10 years with much satisfaction and fulfilment.

Regretfully, recently due to other business and personal commitments, I am unable to dedicate as much time or find as much inspiration as before in running the network and it is with much sadness and sincere regret that I have decided to wind up my business over here.

This has been a very difficult and emotional decision for me to take, having made many friends over the years, but after a good 20 years in the IT-business I feel the time is right to move on and try something else.

So basically I have two choices as I see it:

1. Get someone to take over the system including server and management.

2. Scrap it.

The second choice is not very appealing to me or anyone else, is it?
So...Is there anyone out there who you know would be able to run this system?
I will be more than happy answering any questions you may have.
I can give you a full description of the system upon request. Just email

Today I have removed the ability to subscribe to the network. Hence there are no more subscriptions made. Also the Google advertising is removed.

New account creation works however and users get full access from day one as of now. The old subscribing system can easily be hooked on again if we find a new organisation for DX Tuners.

Please hang in with me as I hope we can find someone to take over the network as soon as possible.

Thank you for your consideration.

Kelly Lindman
DxTuners founder

That letter was followed, several days later, by this one:

Dear DX Tuner Site Operator.

I have briefly been looking for a replacement administration for DxTuners and I have gotten a few offers. Thank you! However, I have found the platform too complex running without my help, so it is with much sadness and sincere regret that I have decided to close down the network.

You are free to shut down your hardware at any point. There will be no stand alone solutions provided by me or my company as we are winding up the business.

I would like to thank you all for contributing to the network over the years. 10 years is a long time and some of you have been with me for most of that time.

Again thank you very much.


Kelly Lindman

My node DX-Pennsylvania (running an Icom 718) went off line on April 20. Since then I have reformatted the hard disk of the machine that was controlling the radio (which was running Fedora Core 5 Linux) and have closed the firewall port to that machine.

If you want to see what DX Tuners was all about, use the Way-Back Machine and check out the site prior to shutdown:

Saturday, February 3, 2007

Samsung YEPP: Another MP3 recorder for DXers?

It seems like it's getting harder to find solid state flash-based MP3 players that also include line-in recording capability. Recent posts on the AM DX email lists have focused on the iRiver models (see my posting on the T30). One unit I have used for portable DX recording is the Samsung YP-MT6. It is very small (less than 1" square, and 2.5" long), barely larger than the AA battery that powers it.

On the side of the unit there is a very nice LCD display with bright backlighting, and the controls (multi-functional, as on most electronics today) are easy to master. The unit features a built-in mic, handy for making field recordings, and a line-in encoding jack (which is unfortunately a small 2.5 mm size plug, not the standard 1/8 inch mini plug one would expect) means you can connect it to a radio for portable recording (I'd recommend using an attenuation cable if the line out of the radio causes overloaded recordings). It also has an FM receiver which, while not super-sensitive, will pick up most local stations in stereo or mono. One very nice feature is the ability to record what's heard on the FM tuner to the player's memory as an MP3 file. That makes it a lot of fun for recording FM stations while travelling. Finally, the unit can be connected to a computer via USB and the recordings transfered as it they were on a memory stick.

Oh yes, it also plays MP3 files quite nicely.

Check eBay, they tend to run in the $15-30 range for 512MB and 1GB sizes.

Tuesday, January 2, 2007

Total Recorder Tip #4 - Lost Recordings?

If you use Total Recorder for overnight, top-of-the-hour or DX test recordings, eventually you'll run into the case where the PC decides to reboot or accidentally turns off in the midst of a recording session (mine did during the Big Sky DX Test night, thanks to Windows Automatic Updates). If that happens, don't worry... more than likely you will be able to recover your recording fairly easily - just follow these steps:

1. Locate the TR "temporary" directory; by default in Windows XP it's in your user profile, and on Windows 98 it's likely c:\Windows\Temp. To check, in Total Recorder go to Options|Settings, click "Open/Save" and see what folder is set for temporary files. For example, on my system it is in c:\Documents and Settings\Local Settings\Temp (if you can't view the contents of that directory, in a Windows folder go to Tools | Folder Options | View and make sure "Show Hidden Files and Folders" is selected).

2. Look for some files of the form ~TRxx.zzz where xx is a letter/number combination and the file extension zzz matches your recording format. For example right now I have several TR sessions running and I see ~TRr1.mp3 and ~TRr2.mp3 since I am recording in MP3 format. If you were recording to "wav" format, the files would end in .wav. When you press the "stop recording" button in TR, or TR abnormally quits, these files stay in that directory with all the audio recorded up to that point. They don't get erased until you say File|New and choose not to save the existing recording (once you do that, though, they're gone).

Update 10-17-2009:

If you do accidentally hit "File|New" without saving your recording, all is not lost. The file still exists on your hard drive but the name has been changed to indicate it is a "deleted" file. DO NOT DO ANYTHING ELSE ON YOUR COMPUTER AT THIS POINT! Any actions you take (even surfing the web) can create files that will overwrite your recording.

Go to another computer and download an "undelete" utility that is compatible with your computer's operating system. I use NTFSUndelete which is a free application. Follow the program's instructions EXACTLY and, as long as nothing has overwritten the TotalRecorder temp file (which again will look something like "~TRr1.mp3") you will likely be able to recover the recording.

3. Rename the temporary files to something that makes sense (like 1460 kHz WXYZ Test 0200 EST 1-2-2006.mp3), and move them to a permanent location. You can listen to them like a normal audio file.

I would say I've had reason to resurrect lost recordings this way a half dozen times in the past year, once due to a family member being "helpful" and shutting my PC down before going to bed, several times due to power failures, and once (and only once on each PC!) due to Windows Automatic Update choosing to reboot my machine in the middle of the night after downloading the most recent updates!

Added 12-16-2007:

I found the following information on the High Criteria web site concerning lost recordings:

My computer suddenly shut down (locked up, re-started) while I was recording with Total Recorder. How can I restore the recorded audio from Total Recorder temporary files?

Go to Options => Settings => Open / Save. Now look in the folder assigned for temporary files. If the temporary files in this folder have .wav or .mp3 extensions it usually means that they are proper audio files.

If the temporary file has ".tmp" extension, it means that you cannot securely extract all recorded audio information from it. This happens because during recording process some information is stored in this file and some information in the PC's RAM.

However it is usually possible to recover most of your data which is stored in this .tmp file in PCM format. This file doesn't have a proper header so you can use our free application TRTmpRecovery (~65 Kb) to add a header. This program allows you to playback any file as a PCM file at different parameter settings (sample rate, 8/16 bit, mono/stereo), select the most appropriate parameters (if the file actually contains audio data) and add a proper header to this file. Once a header is added, this temporary file becomes a valid .wav file.