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!