Tuesday, July 17, 2018

My first decent fix with KiwiSDR TDoA mode

I finally got a good fix on a station with the KiwiSDR TDoA extension.  It's tricky, but for a system available to the public, it works amazingly well.  The instructions that are given from the "Help" button are accurate. That's how you do it.  The secret is indeed to use the minimum possible passband in IQ mode, and to pick relatively close receivers.

Here's a plot of the French 2-megawatt LW time station, made with three receivers. This band is groundwave propagation, with fewer variables than you get with skywave.  The signal is very steady, and comes from a known location, which we see marked by the "TDF" label.  The fix given by the Kiwi system nails the longitude right on, and only misses the latitude by about 30 arc-minutes to the north. That's pretty good.  It's possible that more receivers would have refined the plot further.

Anyway, it works.

Friday, July 13, 2018

KiwiSDR introduces record and TDoA functions

You've probably been playing around with the huge KiwiSDR network which can be reached from http://sdr.hu/ . Just this week, too late to put into the column, it has rolled out a new beta with a recorder and a Time Difference of Arrivial (TDoA) direction finder.

Both seem pretty slick. The recorder is self-explanatory. You click a big red button over on the top right of the control panel, and it starts recording. Click again, and it stops, at which point it downloads to your computer. This will save me having to remember to start a recording application on this computer every time sometime gets interesting. Also, it's possible the recording will be minus whatever net dropouts and errors you get in transit to your machine.  I'm not sure yet, but it sounds logical.

The TDoA has a learning curve.  When I get it to work, I'll write more about it. Basically, it uses the KiwiSDR network as one huge direction finding system, synchronized to GPS time and positions. The user tunes in a station to locate, changes the mode to "IQ" (In phase/Quadrature) and selects other SDRs positioned to receive the signal and give a good solid computation.  That's the tricky part. Ground wave signals work best, favoring the VLF/LF stations. Also sometimes enough receivers can be found near the target.  One can make sure the other SDRs receive the signal too by double-clicking them, which opens them in a new tab.

When it's all set up, click "select" and watch it churn.  It can go for several minutes.  I have yet to have it return a "heat map" with the most likely positions, but others have. For example, someone got a pretty good fix on the 4625 kHz Russian "buzzer" ("UVB-76," S38). The hot spot shown is outside St. Petersburg. In other words, right where I told you it was.

More on the TDoA here.

This could have a major effect on the hobby. More information as it comes.

Tuesday, July 10, 2018

More Night of Nights XIX

RD passes along the following:

The correct station phone number is: +1 415-669-9646 . The number is answered only when the station is on the air.

We mentioned that on-air operations will start at 5:01pm Pacific time (0001Z 13 July) but didn't say how long operations will continue. We usually continue live operations until about 9:30pm Pacific time (0430Z). At that point K6KPH operations cease and KPH and KFS operations are turned over to the transmit site. They continue to broadcast press, weather and special messages until 0000 Pacific time (0700Z). We then hand key the benediction (written by Denice Stoops) from the transmit site and call it a night.

Information for Night of Nights XIX

Is it really 19 years?

Be that as it may, here is full information on the annual triumph of the human spirit also known as MRHS Night of Nights. Notice the absence of the US Coast Guard, not to mention WLO, which has left the air. Be that as it may, the fun continues.



Yes, of course there will be a Night of Nights this year.  And of course, as usual, you are invited to join us on the air or in person for this dramatic and moving event.

What - On 12 July 1999 a ceremony was held at the receive site for coast station KFS at which the last commercial Morse message in the US was sent.  Or so it was thought.  But that was also the date on which the Maritime Radio Historical Society (MRHS) was founded, with the mission to assure that commercial Morse would not perish from the Earth.

Why - Morse code is clearly obsolete, nobody uses it, it's just beeps in the air.  So who cares if it perishes?  The people at that ceremony at KFS cared.  They cared deeply.  Hard bitten grizzled old buzzards who had spent their life at sea as radio officers were weeping.  They were seeing their profession, their passion and, in a way, their life passing away before their eyes.  So it became the mission of the MRHS to make sure that the skills, the culture and the traditions of these men and women would be remembered and preserved through the restoration and operation of one of the greatest of all coast stations: KPH.

Richard Dillman, later to become MRHS Chief Operator, sends one of the last messages on 12 July 1999
Where - Join us at the RCA receiving station, 17400 Sir Francis Drake Blvd. in the Point Reyes National Seashore at the foot of the Cypress tree tunnel.

Cypress tree tunnel
When - 12 July 2018.  Each year on the anniversary of that supposed last message, plus one minute, KPH comes roaring back to the air with all the full throated majesty that mariners around the world heard for decades.  Station KFS will also be on the air as well as amateur station K6KPH which will be standing by for your comments and signal reports.  Doors open at 3:00pm PDT.  The opening message will be broadcast at 5:01pm PDT (0001gmt).

Join us for a complete tour of the station.  Enjoy complimentary radio sandwiches and all the trimmings.  Photograph everything.  Whisper the magic words "True Believer" and be granted access to the fabled Treasure Room where the gems of maritime radio history are kept.

For those of you around the world who will be listening for KPH and KFS or calling K6KPH, here are our frequencies along with the transmitters and antennas that will be used.  The RCA transmitters are 1950s vintage.  The Press Wireless PW15 is from 1942.  The Henry transmitters are 1990s vintage.

Key: EDZ = Extended Double Zepp.  H/2 = H over 2

KPH (5kW):

426          Henry MF5000D  Marconi T

500          Henry MF5000D  Marconi T
4247.0     RCA 252K            EDZ
6477.5     RCA 251K            EDZ
8642.0     RCA 303L            EDZ
12808.5   RCA 304L            H/2
17016.8   RCA 305L            H/2
22477.5   RCA 298H           H/2

KFS (5kW):

12695.5   PW-15                 H/2
17026.0   Henry HF5000D  H/2

KPH and KFS operators will listen for calls from ships on 500kc MF and ITU Ch 3 HF.  Listen on these frequencies if you want to hear the ship side of the QSO.


K6KPH (1.5kW):

3550.0     Henry HF5000D  End-fed wire
7050.0     Henry HF5000D  EDZ
14050.0   Henry HF5000D   H/2
21050.0   Henry HF5000D   H/2

Reception reports and QSLs may be sent to:

Maritime Radio Historical Society
PO Box 392
Point Reyes Station, CA 94956

Monday, July 02, 2018

Lights out at WLO

WLO, Mobile Radio in Alabama, has discontinued most of its services as of 1 July 2018. It was the last of the great old coastal traffic stations in the US. The following was posted to their facebook account:
Sad announcement: It's the end of an era.....after 71 years, WLO will go off the air at 11:59CDT (0459UTC) on 01July2018. A few automated systems/services will continue but there will no longer be 24/7 operators on duty at the Mobile, AL stations. Thank you everyone that liked and commented on this page. I will keep the page up for a while longer.

Leigh (KC4MZT)- Radio/telephone operator, admin