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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

#131

Post by wil421 »

mherdeg wrote: post #83
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.

Lots of reboot NT machine and other IT looking pages. I feel sorry for those sys admins.

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

#132

Post by Fjolsvith »

mschuster91 wrote: post #113
jfalcon wrote: post #73

I think the OP's write up misses one very important piece of the puzzle: Politics. Newt Gingrich who was Speaker of the House at the time got embroiled in an incident that was recorded from a cell phone conversation. https://www.cnn.com/ALLPOLITICS/1997/01/13/tape/index.shtml Now fast forward to a few years later with the Patriot Act and metadata controvery that Edward Snowden exposed... same shit, different day...

> Newt Gingrich who was Speaker of the House at the time got embroiled in an incident that was recorded from a cell phone conversation. I wonder why it's always the same names that crop up as the reason for bullshit regulations.

Signed into law by someone else.

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

#135

Post by MertsA »

grendelt wrote: post #74
FiddlerClamp wrote: post #38

Earlier quoted context omitted.

The funniest thing was that people were convinced that you could cut more diodes (if only you knew which ones) and enable more hidden frequencies. They couldn't understand that this was a one-shot deal. I imagine there were quite a few that ended up destroying their scanners trying.

"Let's see, my crystal radio only has this one diode but it can only receive AM. I bet if I cut it I can hear everything!"

Well funnily enough you can actually get some heavily distorted but still intelligible audio out of an FM channel demodulating it as AM if you shift the frequency over off of the center of the channel and decrease the bandwidth to only get half of the FM bandwidth. First time I heard that while playing around with a SDR I was so confused as to how that was working.

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

#136

Post by sokoloff »

jacquesm wrote: post #128
FiddlerClamp wrote: post #38

Earlier quoted context omitted.

The funniest thing was that people were convinced that you could cut more diodes (if only you knew which ones) and enable more hidden frequencies. They couldn't understand that this was a one-shot deal. I imagine there were quite a few that ended up destroying their scanners trying.

At 15 cents per diode I don't think that would be a particularly expensive fix or worth throwing out an otherwise perfectly good scanner for.

The set of people who just cut away additional diodes under the theory that would unlock further features has minimal overlap with the set who can DIY replace that diode for $0.15.

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

#137

Post by tonyarkles »

jcrawfordor wrote: post #82
giantg2 wrote: post #17

Earlier quoted context omitted.

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 describ…

> I think it might be a good idea to restrict such devices to people with amateur radio licenses

Am a Canadian HAM, and also the owner of multiple transmit-capable SDRs. While I don't disagree with you on principle, one tricky part with that is that the majority of my usage of these devices has been commercial. Requiring an amateur license to do commercial work is kind of the opposite of how the system is supposed to work (i.e. no commercial activity on the HAM bands).

The real saving grace for the transmit-capable SDRs is that they're generally quite low power. I think the most powerful one I have can do... 100mW? Sure, you could be disruptive with that, but it's not going to go very far.

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

#138

Post by ryanianian »

INTPenis wrote: post #117
mherdeg wrote: post #83

Earlier quoted context omitted.

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.

That was super fascinating. I had no idea these existed. People are getting automated messages of Mozilla Mac builds being complete during the disaster. I was 16 when this happened so I had no idea pagers were used like this. Sort of how push messages or chatops is used today. To aide developers or ops people with notifications.

Amazon used skytel pagers for oncall notifications until very recently. I had one in 2014.

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

#139

Post by giantg2 »

tonyarkles wrote: post #137
jcrawfordor wrote: post #82

Earlier quoted context omitted.

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 describ…

> I think it might be a good idea to restrict such devices to people with amateur radio licenses Am a Canadian HAM, and also the owner of multiple transmit-capable SDRs. While I don't disagree with you on principle, one tricky part with that is that the majority of my usage of these devices has been commercial. Requiring an amateur license to do commercial work is kind of the opposite of how the system is supposed to…

"I think the most powerful one I have can do... 100mW?"

Until you add an amp hehe

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

#140

Post by jacquesm »

sokoloff wrote: post #136
jacquesm wrote: post #128

Earlier quoted context omitted.

At 15 cents per diode I don't think that would be a particularly expensive fix or worth throwing out an otherwise perfectly good scanner for.

The set of people who just cut away additional diodes under the theory that would unlock further features has minimal overlap with the set who can DIY replace that diode for $0.15.

I highly doubt that. Cutting away a diode means you have some tools, aren't afraid to 'void the warranty' and likely means that you know what you're doing. Those are likely people who also have a soldering iron sitting around somewhere and know how to use it.

Everybody else would have someone else cut that diode in the first place.

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