Scanner Tales: Is that a cordless phone or a high-power repeater usurper?

Now for something a little different with Scanner Tales: Short one-off stories about specific events. Enjoy!

I got a call from a friend who was at the time the Village President of a small town next to the one I was a police officer in. As a Ham and the trustee of one of the larger ham repeater clubs in the area he and I often had a lot to discuss. One day he called me and asked for help tracking down a transmitter of some sort that was blasting away on the input to one of their repeaters and causing all kinds of havoc. He was able to pinpoint the location of the transmitter to an area on the west side of my town.

I met him in the area and as all I had with me at the time was a PRO43 scanner and all he had was his 440 band handheld we had to improvise a bit. We drove around the area until we were able to hear the transmitter on his handheld. We figured it was slightly off-frequency for his repeater input but strong and close enough to interfere with it. We could hear voices but could not make out what was being said. Was it a different language, distorted by being off-freq or both?

Next we tuned my PRO43 to the same frequency and were able to hear it. We then removed the antenna off the scanner and drove around to where we could hear it without the antenna connected. It turned out to be right in front of a large home. We were pretty sure that this was the source.

We knocked on the door and the resident opened the door. We explained we were trying to locate the source of some radio interference. The lady was Asian and spoke very broken English. I assured her they were not in trouble and we were not there as the police, but just to figure out what was interfering with the radio system. She called her maid, who was bilingual and then they invited us in to try to find the source. Just then it stopped. She called upstairs to her daughter, who came down carrying a cordless phone of a type I had never seen before. We asked her to make a call and as soon as she pressed the button on the phone the noise came up.

They showed us the phone, it turned out to be a Chinese model they brought back from China a month or two before, about the same time the interference had started. We looked at it and from what we could figure out, it transmitted 10-15 watts on 448.31275 (I could be wrong on the freq, it was 40 years or so ago…). We told her that it actually was not allowed to be used in the USA as it was not type accepted and on frequencies not allowed for cordless phones as well as at too high a power level. They agreed to dispose of the phone and we never heard it again. We thanked them and took our leave.

 

[buddrousa]

Uniden had a extra handset and charger.

 

[mule1075]

I used to hear quite a few cordless phones on 46 and 49 Mhz. I have heard neighbors making drug deals. Baby monitors were also popular.

You would be surprised how many people still use them. At least in my area still and the conversations are still the same.

 

[rf_patriot200]

You would be surprised how many people still use them. At least in my area still and the conversations are still the same.

There are Two of the 902-928 mhz. variety still working in my complex.

 

[kc2asb]

You would be surprised how many people still use them. At least in my area still and the conversations are still the same.

Definitely a bit surprised. I guess as long as handset batteries are still available they can be kept going.

 

[rf_patriot200]

Definitely a bit surprised. I guess as long as handset batteries are still available they can be kept going.

Batteries America stock several varieties of those little 3.7 volt flat packs, so if people need to replace them, there's a source.

 

[radionx]

I remember taking a Uniden Cordless Phone running power and phoneline up my 80 foot tower mounting everything in a waterproof box antenna out of the bottem. The cordless phone would work over 12 blocks away. This was 1979-1980

Same here, around 1995. CT1+ Phones on 900MHz could reach quite far, I modified the antennas on them, up to 1.6 Miles were possible. We even had speech inversion on them.

They did not directly implement FHSS but changed channel on every call and had a sync beacon every 30s or so, which checked if the handeset was legit.

 

[kc2asb]

There are Two of the 902-928 mhz. variety still working in my complex.

Those 902mhz phones are in the clear? Thought by then they had some kind of voice inversion.

 

[EAFrizzle]

I kept the 49 and 900 MHz channels in most of my scanners back then. I need to check them out again.

 

[nd5y]

Those 902mhz phones are in the clear? Thought by then they had some kind of voice inversion.

There are different types. Analog FM and several digital modes.

 

[kc2asb]

I kept the 49 and 900 MHz channels in most of my scanners back then. I need to check them out again.

+1. I thought almost zero chance of hearing anything on either band.

@nd5y -Thanks!

 

[KT4HX]

These higher power cordless phones were also popular in Iraq, during the Global War on Terror(ism)......and they caused problems in more ways than one. But, were easier to direction find than sniffing out a specific cell phone with a "fish" named Harris device or DRT branded receiver.

Yeah, I remember those when I was working for the USG back around 2002. I had been at one location and some signal would periodically wipe out our encrypted tactical satellite comms. The next time I went to that location I took my Pro-43 with me and monitored the frequencies around that of our comms to see if I could find out what it was. Turned out it was one of those phones as I could hear the conversations in Arabic, and the signal was very strong. Consulting with others, I was told that often times one person in a neighborhood would have them, and they would allow their neighbors to use the phone at times. It sure was a real PITA from time to time!

 

[rf_patriot200]

Those 902mhz phones are in the clear? Thought by then they had some kind of voice inversion.

I remember a couple models from Uniden did have single inversion scrambling on them, and could even be used as a intercom between handsets.

 

[MTS2000des]

Nothing was more fun than a low band high split Motorola MT1000 programmed for 43/49MHz cordless phone pairs. Nothing.
With a receiver that could hear the base units a mile away, and 6+ watts of raw transmit power, one could OWN your phone.

 

[rf_patriot200]

Nothing was more fun than a low band high split Motorola MT1000 programmed for 43/49MHz cordless phone pairs. Nothing.
With a receiver that could hear the base units a mile away, and 6+ watts of raw transmit power, one could OWN your phone.

WHY would you want to interfere with someone's right to make a phone call though ?

 

[Echo4Thirty]

Back in the 90s there was a local 2m repeater located on the tower at the owners house. He decided to be nice and put an open autopatch on the repeater. He connected it to his house phone and forgot to tell the family. You could bring up the autopatch and his wife could be in the middle of a call. Often the patch would time out at 10 minutes and someone would bring it back up to listen more. I guess she eventually figured it out and the patch got taken down.

 

[rf_patriot200]

Back in the 90s there was a local 2m repeater located on the tower at the owners house. He decided to be nice and put an open autopatch on the repeater. He connected it to his house phone and forgot to tell the family. You could bring up the autopatch and his wife could be in the middle of a call. Often the patch would time out at 10 minutes and someone would bring it back up to listen more. I guess she eventually figured it out and the patch got taken down.

Oops !

 

[70cutlass442]

In the early 2000's I used my first paycheck at my high school job to buy a long-range cordless phone. It was in the 200 MHZ range (quite possibly military). These were sold on ebay and the kit came with an outdoor antenna, about 75' of LMR400ish cable, a base that was about the size of a directv reciever, and the handset had a 2' long telescopic antenna.

I could talk across the city (about 6 miles) on this thing. Short of some testing, I never really used it for fear of causing interference to go knows what it was sharing spectrum with. It was a neat thing to try but didn't have a real practical use for me.

 

[ratboy]

I had a neighbor who used to be very entertaining to listen to. She lived right behind and one house over from mine, and she was amazingly cheap. Her kids and husband used to imitate her to each other, and talk about how much money she had saved on something. One day, she was talking about her latest bargain with her daughter who lived in Atlanta, and suddenly, a dial tone and touch tones totally covered her up. There was a girl on the stronger signal ordering pizza, and when she gave them her address, I was pretty shocked, she was about 3/4 of a mile away. I called a friend who lived over 7 miles away, and he could hear her without any problems on his scanner on 46.710MHZ! The neighbor could hear her in the background when she was talking, so it had to be pretty powerful. For about 6 months, I would hear that family talking on that phone and one day, it was gone, replaced by a new cordless phone that my neighbor had no problems with. I always wondered what happened to the super powerful phone...

Before that, we had a neighbor who had an amazingly strong baby monitor that I could hear the kid singing songs in his crib while his parents screamed and yelled in the background. They fought all the time and finally, the husband left. I would become way more involved with that family when in 1999 my dog King hooked up with their dog that ran loose, and produced a litter of 9 pups. They kept one, named him Dilbert, and eventually I got to hear all about the crazy mom and why dad finally left. King and Dilbert didn't get along very well, but everytime I walked King, he would drag me over to Dilbert's house, where they would stare at each other and get very tense for a few minutes. That baby monitor came and went and eventually, the baby I heard on it was the son of the kid who used to sing to himself. Eventually the crazy mom lost her job after being arrested at local protests many times, and they had to sell the house. No more baby monitor and kid drama. The new neighbors had digital cordless phones that couldn't be listened to.

 

[kc2asb]

. There was a girl on the stronger signal ordering pizza, and when she gave them her address, I was pretty shocked, she was about 3/4 of a mile away. I called a friend who lived over 7 miles away, and he could hear her without any problems on his scanner on 46.710MHZ! The neighbor could hear her in the background when she was talking, so it had to be pretty powerful.

With the right conditions, who knows how far that signal may have ultimately traveled!

 

[BinaryMode]

This is why back in the day I bought a 900 MHz spread spectrum cordless phone. And I tested it with my scanner to make sure I couldn't pick myself up, too!

Not the most secure thing in the world, but kept the "normies" from hearing me. I've read the PN code for all spread spectrum phones were the same. Not sure how true.

Best on the market now would have to be a TDMA version EnGenius.

My current cordless phone is DECT 6.0, and I verified it uses encryption. What type of encryption I don't know. What I do know however is that with the right hardware and a Great Scott Gadgets HackRF One you can monitor DECT 6.0. Because I knew that I called my cordless phone manufacture and asked if the phone used encryption. The lady pulled out the company manual and confirmed it did. I'd like to get an EnGenius version.