Thursday, August 29, 2013

STANAG 4285 - the motorboat signal all over the shortwave bands

Many shortwave listeners wonder what is this strange "motorboat like" signal, that is heard with strong signal all over the shortwave bands. Is it a jammer of some kind? Or it's a local interference? No, this is the so-called STANAG 4285. If you wonder what is STANAG, please check the Wikipedia article on it. STANAG-4285 is a standard for the characteristics of 1200/2400/3600 bit/s single tone MODEMs that are used for HF radio links between the NATO military bases. These military bases do transmit on virtually all shortwave bands - from 2 to 26 MHz. Here is a list of frequencies, compiled by Mr.Eddy Waters from Australia:

4041.5 4055.2 4112.6 4152.0 4169.0 4225.5 4228.0 4236.2 4237.2 4244.6 4253.2 4255.0 4263.2 4278.2 4280.6 4299.2 4305.2 4306.0 4307.2 4310.2 4317.2 4345.0 4346.0 4347.5 4372.0 4376.2 4401.8 4509.7 4532.7 4572.5 4576.2 4588.6 4590.0 4603.2 4643.0 4680.1 4686.0 4687.2 4781.7 4808.2 4810.2 4901.0 5048.0 5085.2 5101.0 5102.2 5148.2 5235.7 5246.2 5266.6 5278.0 5278.2 5278.6 5279.7 5282.0 5309.7 5332.0 5336.5 5348.2 5361.7 5362.2 5379.0 5427.7 5700.0 5732.7 5784.7 5786.5 5789.7 5848.2 6227.6 6249.2 6251.0 6253.2 6258.2 6259.2 6286.7 6335.2 6343.2 6360.6 6382.2 6388.7 6393.2 6398.7 6403.2 6405.2 6408.5 6408.7 6419.2 6423.2 6424.0 6428.2 6429.2 6442.2 6443.2 6465.0 6472.2 6490.5 6492.7 6493.2 6500.7 6711.2 6765.0 6780.7 6781.2 6787.7 6793.2 6794.5 6805.2 6842.6 6843.2 6881.0 6889.6 6892.0 6893.2 6903.2 6903.2 6968.0 7405.2 7406.2 7420.7 7467.2 7467.7 7601.2 7723.0 7776.7 7800.0 7843.2 7853.2 7982.0 8005.0 8008.2 8022.2 8027.2 8049.7 8073.7 8082.0 8098.2 8106.7 8108.5 8109.7 8138.0 8138.2 8156.2 8170.2 8170.5 8172.0 8178.2 8248.0 8271.2 8300.2 8340.0 8355.0 8456.2 8463.2 8468.2 8470.0 8474.2 8488.2 8508.0 8511.0 8524.2 8540.2 8541.0 8542.0 8552.6 8573.6 8612.2 8612.2 8618.2 8632.6 8661.0 8672.2 8695.2 8697.4 8698.2 8708.2 8793.6 9005.0 9028.6 9052.7 9095.0 9098.6 9100.5 9132.0 9270.0 9910.7 9956.2 10012.0 10111.5 10170.2 10186.1 10233.2 10264.2 10274.2 10352.2 10352.2 10353.2 10371.2 10408.2 10439.6 10449.7 10478.0 10499.7 10522.0 10555.5 10559.2 10561.0 10568.2 10568.7 10568.7 10569.2 10599.0 10658.2 10669.2 10740.0 10741.7 10742.0 10751.6 10758.2 10778.2 10807.2 10807.7 10836.7 10948.2 10948.7 10967.2 11000.0 11006.2 11015.0 11016.7 11021.2 11042.7 11072.7 11105.2 11200.0 11228.0 11405.5 11414.0 11455.2 11457.0 11538.2 11540.0 12144.6 12154.2 12193.0 12203.2 12221.0 12275.0 12305.7 12368.2 12386.0 12396.0 12406.0 12416.2 12568.0 12570.0 12661.2 12685.2 12691.2 12692.0 12704.5 12715.2 12724.0 12749.2 12771.0 12784.2 12804.2 12829.2 12847.2 12860.5 12873.6 12883.6 12883.7 12913.0 12915.0 12930.7 12932.2 12958.0 12958.2 12982.0 13057.6 13072.2 13091.5 13410.0 13410.7 13411.6 13413.7 13415.5 13445.0 13495.0 13588.2 13917.2 13919.0 14320.0 14371.5 14376.2 14385.2 14388.2 14442.2 14616.0 14638.2 14723.7 14749.2 14870.0 14901.0 15000.0 15851.0 16000.0 16028.2 16030.0 16158.2 16205.0 16225.0 16250.0 16270.2 16333.2 16356.7 16456.5 16574.2 16589.2 16611.6 16656.0 16748.2 16790.0 16905.0 16916.2 16921.8 16924.2 16925.0 16931.0 17060.6 17082.2 17097.6 17106.6 17125.7 17130.0 17135.6 17179.6 17192.6 17197.5 17200.2 17202.2 17218.7 17219.0 17237.7 17378.2 17799.2 17930.2 18045.0 18259.2 18366.0 18367.5 18375.2 18493.5 18507.2 18532.7 18538.0 18555.0 18598.4 18853.2 18855.0 19714.2 19729.2 19730.2 19737.7 19800.0 19830.2 19898.2 20000.0 20010.2 20151.0 20160.2 20192.0 20290.0 20975.2 22178.5 22188.2 22413.0 22544.6 26130.2

Some of these are very strong and you may hear them round the clock, but, of course, it depends on your location. At my QTH in Central Bulgaria, I am able to hear STANAG-4285 signals from Italy, Germany and other European countries with relatively good signal on 5 and 6 MHz round the clock, even in the summer. I have no idea of the transmitters, but wouldn't be surprised if they use output power of up to several kilowatts.
The signal itself consists of several sub modes (75-2400 bps) and two different interleaving options (short and long). The waveform consists of a 1800 Hz carrier with PSK modulation.
Most of the traffic is encrypted, but there are some stations that are not. The Sigmira software does an admirable job decoding STANAG-4285 traffic. Here are some examples:


I hope you're now familiar with what is called STANAG-4285, the motorboat signal that appears all over the HF bands. If you're interested in receiving utility stations and decoding digital links, do not hesitate to join the UDXF mailing list at http://groups.yahoo.com/group/udxf/ 73!

1 comment:

  1. What about those transmissions which actually SOUND like modems, AKA data transmissions (or if you could imagine amplifying the sound on my Windows computer when the green light in front turns yellow rapidly, indicating that the computer is downloading something)??? I've noticed one such "station" on between 7300 - 7400 kHz (my non digital dial prevents a more accurate frequency reading) once Radio Dabonga and the BBC leave 7315 and 7325 respectively at 06 UT in my part of the world (Eastern NA), clearing that part of the spectrum for such transmissions. Perhaps someone out there would know what it is (it is definitely NOT the motorboat sounds I've heard linked to here nor any apparent frequency jammer). I still remain, your intrepid reporter

    Shawn From Flushing NY
    (the semi-authority on all things HM01 related)

    ReplyDelete