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Why radio receivers won’t tune 800-900 MHz

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Re: Why radio receivers won’t tune 800-900 MHz

#81

Post by foepys »

jcrawfordor wrote: post #42
breput wrote: post #10

I had (and probably still have) a Radio Shack Pro-2006 scanner from the late 80's. Even pre-Internet, instructions on how to bypass the cellular band block were easily found on Fidonet and local BBSes, and all it involved was removing a single diode. https://www.wentztech.com/radio/Equipment/Pro2006/pro2006mod... It was really a golden time for snoop...er..listening to cellular phones because they were so enormously…

Cordless phones are a whole different and rather interesting topic. The huge security issues with early cordless phones lead to DECT (or technically DECT 5.0) becoming widespread in the US, and it's actually a rather interesting protocol with a very complex and rich set of capabilities considering we normally only see it used for simple cordless phones. IP over DECT is an uncommon but interesting application.

There are some smart home devices that use DECT Ultra Low Energy to communicate with their base station. It's a pretty cool tech because DECT uses its own frequency band and doesn't interfere with bluetooth or wifi in the often highly congested 2.4 and 5 GHz bands. Even firmware updates are possible because the bandwidth is large enough to push some megabytes through.

Re: Why radio receivers won’t tune 800-900 MHz

#82

Post by jcrawfordor »

giantg2 wrote: post #17
LeoPanthera wrote: post #2

*in the USA. Radio receivers and scanners sold outside the USA, even if they are made inside the USA, have no restrictions. US manufacturers usually label these radios as "export" versions. It reminds me of the early days of web browsers when "export" versions of Netscape and IE only supported a maximum of 56-bit encryption for SSL.

I would imagine SDRs with "export" software are easy to get and can tune in.

A large portion of SDRs have no FCC equipment authorization at all, and so don't necessarily comply with regulations---including the lack of an AMPS lockout. This makes them a little bit iffy for sale in the US, but there is generally a rule that allows "test equipment" to be sold without equipment authorization under certain conditions on its use. I (not being an expert on this, I am not a lawyer, etc) would describe most hobby SDR use as being a gray area, but one that is probably not of too great concern since most hobby SDRs on the market are receive-only and obviously these weird part 15 rules about scanning receivers don't really matter in the modern age.

SDR transceivers like the HackRF are probably still not being purchased by people who will cause any trouble, but I do worry a little bit more about unintentional disruption of important radio applications like aviation navaids or whatever. If I were to take a policy angle here, I think it might be a good idea to restrict such devices to people with amateur radio licenses since they are not especially hard to obtain (DE AE5JL). I'm sure there's a thousand people here who would vehemently disagree with me on that though.

Re: Why radio receivers won’t tune 800-900 MHz

#83

Post by mherdeg »

breput wrote: post #10

I had (and probably still have) a Radio Shack Pro-2006 scanner from the late 80's. Even pre-Internet, instructions on how to bypass the cellular band block were easily found on Fidonet and local BBSes, and all it involved was removing a single diode. https://www.wentztech.com/radio/Equipment/Pro2006/pro2006mod... It was really a golden time for snoop...er..listening to cellular phones because they were so enormously…

Roughly in this genre, the 9/11/2001 pager text data ( https://911.wikileaks.org/files/index.html ) are an interesting peek inside people's putatively private conversations.

Re: Why radio receivers won’t tune 800-900 MHz

#84

Post by jcrawfordor »

foepys wrote: post #81
jcrawfordor wrote: post #42

Earlier quoted context omitted.

Cordless phones are a whole different and rather interesting topic. The huge security issues with early cordless phones lead to DECT (or technically DECT 5.0) becoming widespread in the US, and it's actually a rather interesting protocol with a very complex and rich set of capabilities considering we normally only see it used for simple cordless phones. IP over DECT is an uncommon but interesting application.

There are some smart home devices that use DECT Ultra Low Energy to communicate with their base station. It's a pretty cool tech because DECT uses its own frequency band and doesn't interfere with bluetooth or wifi in the often highly congested 2.4 and 5 GHz bands. Even firmware updates are possible because the bandwidth is large enough to push some megabytes through.

That's very cool. When I was a kid, a nearby department store (Fred Meyers on 39th and Hawthorne) used a large-scale DECT system for employee-to-employee and paging. Each staff member carried what was essentially a ruggedized cordless phone with an earpiece and they heavily used DECT's "intercom" handset-to-handset feature to talk to each other, and it was all on a PBX with their outside phone lines. I believe it was a Panasonic system. Panasonic seems to still offer such a setup that uses IP for coordination between the multiple DECT "cells," but I'm not sure what was in use at the time. I remember it giving me an overwhelming feeling that my home's DECT cordless phone was a disappointment to the technology's capabilities.

For that matter I once had a job where I had a WiFi IP phone that I carried around, but I think cellphones have gotten cheap enough for corporate users that the wind is out of those sails. I keep thinking about buying one of those on eBay...

Re: Why radio receivers won’t tune 800-900 MHz

#85

Post by tomcam »

dmitryminkovsky wrote: post #71
o-__-o wrote: post #28

Earlier quoted context omitted.

Not op, but fun story to share. The year was 1999, I had befriended a strange group of friends from an IRC support channel. We all lived within 250 miles of each other and one day decided to have a gathering with about 6-7 randoms from the channel. Hilarity ensued as we played games of command and conquer, Starcraft, and Serious Sam. I was yelled at for saturating the 1.5mbps SDSL line with my webcam, streaming views…

> Someone else was eating aluminum soda cans Huh?

Well they had pretty much phased out steel cans by that time

Re: Why radio receivers won’t tune 800-900 MHz

#86

Post by rasz »

>not particularly difficult to intercept the call setup process from an AMPS phone and swipe its identification numbers, allowing you to basically steal someone else's cellular service. You can imagine that this was popular with certain criminals with a need for untraceable but convenient communications.

and Kevin Mitnick https://www.cnet.com/news/q-a-kevin-mitnick-from-ham-operato...

"I was cloning my cell phone to random subscribers and dialing into computers from the cell phone."

Re: Why radio receivers won’t tune 800-900 MHz

#87

Post by 01100011 »

ed25519FUUU wrote: post #16
breput wrote: post #10

I had (and probably still have) a Radio Shack Pro-2006 scanner from the late 80's. Even pre-Internet, instructions on how to bypass the cellular band block were easily found on Fidonet and local BBSes, and all it involved was removing a single diode. https://www.wentztech.com/radio/Equipment/Pro2006/pro2006mod... It was really a golden time for snoop...er..listening to cellular phones because they were so enormously…

Stories please!

Honestly I never heard anything interesting on either analog cell phones or cordless phones. Messing with drive-thru intercoms with our modified Icom W2-As was a hell of a lot more fun.

Re: Why radio receivers won’t tune 800-900 MHz

#88

Post by Lammy »

dmitryminkovsky wrote: post #71
o-__-o wrote: post #28

Earlier quoted context omitted.

Not op, but fun story to share. The year was 1999, I had befriended a strange group of friends from an IRC support channel. We all lived within 250 miles of each other and one day decided to have a gathering with about 6-7 randoms from the channel. Hilarity ensued as we played games of command and conquer, Starcraft, and Serious Sam. I was yelled at for saturating the 1.5mbps SDSL line with my webcam, streaming views…

> Someone else was eating aluminum soda cans Huh?

https://en.wikipedia.org/wiki/Pica_(disorder) maybe?

Re: Why radio receivers won’t tune 800-900 MHz

#89

Post by pessimizer »

sterlind wrote: post #26
heavyset_go wrote: post #20

Earlier quoted context omitted.

Now, not only does someone not need to be actively listening, they don't even need to save the audio. Just convert it to text, keep it indexed and whatever three letter agency is doing the tapping has an easily searchable record of your communications should they ever feel the need to look into you without you knowing.

Converting to text loses data and will fail on unexpected languages or accents. It's better to use a specialized voice codec, which can have fantastically high compression rates, or just keep the (already annoyingly-companded) 8kbit voice stream around in its entirety. It's pretty small.

You convert it to text in order to index it. If it becomes interesting in the future, you listen to the audio (maybe after getting permission from a judge in a secret court.).

Re: Why radio receivers won’t tune 800-900 MHz

#90

Post by jimmyrocks »

molticrystal wrote: post #58

As a child in the 80s I was given an intellivision and a old (even in those years) ~13" black & white tv to play it on. It had the ability to tune to the higher UHF channels 70-83 [0] which while planned for use in tv broadcast, never ended up being used, but they didn't know that at the time of the construction of the tv set. The frequency covered by those channels were reallocated in 1982 by the CCIR worldwide conv…

I had a TV that did this exact same thing! Except I was given it as a color "monitor" for an Apple IIE. I would spend hours building my own antennas and spinning the fine tune knob to try to bring in far away signals.
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