MTR

WWV & WWVH - interference from China BPM - Radio Jamming QRM - Spanish

Intoduction to WWV & WWVH

For those who enjoy the hobby of shortwave listening (SWLing for short), you may have undoubtedly tuned to the WWV and/or WWVH time standard stations at one time or another. For many listeners it's a useful tool, from its intended purpose of synchronising clocks and watches right through to checking up on radio signal propogation conditions.

If you don't know about the station, see if you can find it on the dial next time you listen. Simply tune your shortwave receiver to 5, 10, 15 or 20 MHz in AM mode. The 5 and 10MHz signals are best during the evenings, and 15/20 MHz are best during the day. The station denotes each second with a 'pip' type of sound, which approximates a clock ticking. On most minutes, a continous tone is played between each tick from 01 through to 45 seconds, which helps finding the station easier.

Interference: BPM

Anyone who has been frequently tuning into WWVH may have noticed another station sharing the same frequency, also broadcasting a similar time signal. If you live in areas near the Pacific, Asia pacific or even Asia itself, you will most likely come aross this issue.

Sometimes, the second 'pips' (ticks) from WWV/WWVH are heard along with longer 'beeps'. In some cases, the beeps completely cover up the pips. This occurs from minutes 25-29 and 55-59 of each hour. To confirm this, keep listening; as soon as the time hits 30 minutes past the hour or on the hour, the long 'beeps' should cease and only the WWV/WWVH pips should be heard.

The BPM time signal is known to output UT1 time beeps during those minutes, and in some cases, the tick from BPM can be out of sync with WWV by as much as several hundred miliseconds, leading to 'double ticks', or a 'tick-beep' type of effect. The out-of-sync time signal can cause problems if you're trying to use the signal to accurately set a timekeeping device.

On the 29th and 59th minute of each hour, the interfering station (BPM) plays loud morse code for the first 40 seconds, then an announcement in a female voice identifies the station as 'BPM' followed by a Mandarin announcement. The morse code usually covers up the station ID announcement from WWV/WWVH.

China has no respect to other users of the Electromagnetic Spectrum

The signal originates from China, whom in their wisdom, has decided to run their own time-standard radio stations, transmitting on the exact same frequencies of WWV and WWVH. The governments of China simply have no respect of the existing WWV stations and have gone ahead and tried to transmit over the top of them, causing problems for everyone worldwide. For them to play their station ID at exactly the same time as WWVH is simply plagiarism. China are big industrial polluters (ecologically), and for them to pollute the airwaves like this and to have little regard of existing users of the Electromagnetic Spectrum is of no surprise. This must stop!

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