The following may be useful for your Amateur Radio interference files.
On October XX, 201XX, we were preparing to participate in a regularly scheduled Amateur Radio Emergency Service exercise on the VE3YYZ 70 centimeter repeater on 443.050 MHz At 5:35 PM, about five minutes after the start of the net, a strong interfering signal on the repeater input frequency of 448.050 MHz interfered with the transmissions of the net control station and several other participants.
At first, the interfering signal had no modulation, and later sent random DTMF telephone tones continuously and music. There was also abusive language and racist remarks made. There was no voice or CW identification.
After about 5 minutes of the interference, we began to use automated radio direction finding equipment to DF the interfering signal. We also had engaged several rovers using a four element Arrow antenna feeding a Yaesu FT-7900 FM transceiver through a step RF attenuator.
Our starting point was the intersection of Highway 404 and Steeles. The interference continued, with transmissions lasting about one minute, and occurring about every few minutes. There seemed to be no attempt to single out any particular station for jamming. When we were about a block from the transmitter’s location, the signal was so strong that all available attenuation (110 dB) did not sufficiently reduce the signal in to the receiver for bearings. We completed the search using an amplified field strength meter connected to the antenna and a DF loop antenna for 446 MHz A later check of the field strength meter setting showed that the signal from the antenna exceeded 5000 microvolts with the car parked directly across the street in front of the property where the transmitter was located.
Bearings from several locations along the street showed that the interfering signal was emanating from 1XXX XXXXX Street. The property contains several amateur HF and VHF antennas. Of the two vehicles in the driveway, one had license plate VE3XX.
The interference was in progress when we pulled up in front of the property at 5:55 PM. It then immediately ceased and did not re-occur.
We remained in the area for 15 minutes and heard no further transmissions on 449.050 MHz from that property. No attempt was made to make contact with the residents.
Further surveillance activity has demonstrated additional intentional interference on other repeaters in the GTA area from this location.
Bravo Sector Radio Club Enforcement Unit