World War II radio & radar history (4)

More YouTube videos related to World War II radio, SIGINT and radar:

BC-375 transmitter, used in B17 "flying fortress" bombers


Still active: ROS network on 27635 kHz

Freebanders using ROS, heard on 27635 kHz
The digital freebanders' network on 27635 kHz (11 m), described in a post on 2017-04-06, remains active. The current (July 22) Es openning in Europe allowed strong signals into Greece from Maidenhead locator fields JN and JO. Stations in this extensive network use the ROS MFSK protocol calling CQ or transmitting beacons in various data rates (4, 8 and 16 baud). 

Fortunately PSK reporter supports 11m activities and allows plotting the stations on a map.


The beacon on the waterfall on my Perseus SDR

The COMMON AND PRECIOUS propagation beacon, which used to operate on various frequencies like 10237.6 kHz, recently recently moved to 6398.5 kHz. 

The beacon operates in CW and transmits the message: "JO62SK 52W DIPOLE JO62SK COMMON AND PRECIOUS". Yesterday evening it was received on my Perseus SDR with very good signal.

The string JO62SK is a Maidenhead locator centered at Aldershof, a German town southeast of Berlin.

See related previous posts on this blog:
COMMON AND PRECIOUS update (TNX QSL) (2015-09-10)

For background information about the beacon, read article "Common and Precious 4" on the HF Underground wiki.


DAB/DAB+ digital radio in Thessaloniki, Greece

In a previous post I discussed the ERT DAB+ multiplex covering Athens, Greece. Recently the government controlled broadcaster ERT started transmitting a second  DAB+ multiplex from their transmitter site on Mt Hortiatis, near Thessaloniki. (HGRS87 coordinates: 423700, 4494181; WGS84 coordinates 40.5975 N - 23.1000 E; 871 m ASL).

This second experimental ERT transmssion on 174.928 MHz (Channel 5A) covers most of Thessaloniki and part of Central Macedonia Region. The multiplex contains the following audio streams:

"PROTO" (136 kbps,  AAC)
"DEYTERO" (136 kbps, AAC)
"TRITO" (136 kbps, AAC)
"ERA SPORT" (128 kbps, AAC)
"KOSMOS" (136 kbps, AAC)
"Voice of Greece" (96 kbps, AAC)
"ERA 7" (64 kbps, AAC)

The channel characteristics were logged in the afternoon of Sunday, April 29, 2018 using a Perstel DR70tc portable FM/DAB receiver at various locations in downtown Thessaloniki. 

A second multiplex under the name of "Sigmacom DAB+" is also transmitted from an unknown location in or near Thessaloniki on 225.648 MHz (Channel 12B). On April 30, 2018, it carried six private stations:

"YELLOW 92.8" (96 kbps, AAC)
"COSMORADIO" (96 kbps, AAC)
"KALAMARIA FM" (96 kbps, AAC)
"MORE RADIO" (96 kbps, AAC)
"AROMA FM" (48 kbps, AAC)
"PLUS RADIO" (96 kbps, AAC)

This seems to be an experimental transmission by local rado equipment supplier Sigmacom Broadcast Ltd. According to the official Digital Radio Allocation Plan for Greece, channel 12B would carry the 5th DAB multiplex for Thessaloniki area.

Update: Official service announcement by Sigmacom, 2018-04-30. Their transmitter site is also on Mt Hortiatis.



DAB/DAB+ digital radio in Greece

A few weeks ago, the government controlled broadcaster ERT started transmitting a DAB+ multiplex from their transmitter site on Mt Ymittos, near Athens (HGRS87 coordinates: 483892, 4200920; WGS84 coordinates: 37.9583 N - 23.8183 E; 945 m ASL). Before that, the Minsitry of Digital Policy, Telecommunications and Information had published two relevant ministerial decisions in the Government Gazette. Decision 169/2018 defines the allotements and frequency allocations for DAB broadcasts in VHF Band III (174-230 MHz) and authorized a number of transmitter locations. Decision 170/2018 issues a license to ERT for nationwide DAB+ broadcasts on one frequency in each allotment.

Currently an experimental ERT transmssion on 227.36 MHz covers only part of Attica Region. The multiplex contains the following audio streams:
  • "PROTO" (136 kbps,  AAC)
  • "DEYTERO" (136 kbps, AAC)
  • "TRITO" (136 kbps, AAC)
  • "ERA SPORT" (96 kbps, AAC)
  • "KOSMOS" (128 kbps, AAC)
  • "Voice of Greece" (96 kbps, AAC)
  • "ERA 7" (64 kbps, AAC)
The channel characteristics were logged in the afternoon of Satruday, February 24, 2018; they may change over time while ERT engineers experiment with coverage and sound quality issues. 

Voice of Greece is also transmitted at irregular times, usually during late nights, in short wave, on 9420 kHz.  

"ERA 7" transmits audio from the sessions of the Greek Parliament. 

"TRITO" is supposed to transmit high fidelity music, however the current bitrade is inadequate, as 192 - 256 kHz is the minimum acceptable bitrate for this purpose.

My vintage MagicBox Clarus Plus DAB/WiFi digital desktop radio receiver can receive all seven channels with its whip antenna, however the signal strength is weak and the error rate relatively high.

For general and technical information about DAB, access to the relevant ETSI standards and other updates, visit the WorldDAB Forum at: https://www.worlddab.org/ 


DP0GVN: WSPR beacon received on 30m

WSPR beacon DP0GVN (see previous post), located at at the German Antarctic Research Station "Neumayer III", transmits regularly on 30 and 20 m (10 and 14 MHz). 

This evening its weak signal is decoded in Greece. The radio is an IC-706 MkII with a vertical antenna and WSJT-X v1.8.0 software. 

Here are the first three WSPR packets:

1804  -26   0.3   10.140158    4   DP0GVN        IB59     33  12316
1816  -27   0.3   10.140158   -4   DP0GVN        IB59     33  12316
1828  -26   0.4   10.140159   -2   DP0GVN        IB59     33  12316

DP0GVN: WSPR beacon in Antarctica

A few days ago, the ARRL site announced that DARC, in cooperation with two German universities, would install a WSPR receiver and beacon in Antarctica. The receiver is based on the Red Pitaya development board, which can function as an SDR transmitter and receiver. The callsign would be DP0GVN. 

According to the entry in QRZ.COM, DPØGVN is a club station located at the German Antarctic Research Station "Neumayer III" in Dronning Maud Land, Antarctica. The call sign is regularly being activated by station personnel as well as visitors.

This morning I transmitted on 40 m (7 MHz) WSPR with 5W and I was glad to see on WSPRnet that DP0GVN received my signal and reported it to the server. 

Timestamp    Call    MHz    SNR    Drift    Grid    Pwr    Reporter    RGrid    km    az
2018-01-22 02:34      SV1XV      7.040074      -20      -1      KM18ua      5      DP0GVN      IB59uh      12356      191
2018-01-22 02:12      SV1XV      7.040072      -18      0      KM18ua      5      DP0GVN      IB59uh      12356      191
2018-01-21 18:20      SV1XV      7.040074      -26      -4      KM18ua      5      DP0GVN      IB59uh      12356      191

Now I hope to receive their WSPR signal, they transmit with 5W on a vertical antenna, usually on 10 and 14 MHz, but the noise level at my location is much higher.