Cell phone frequencies

[KB4MSZ]

I see there is a fair amount of "wiggle room" for manufactures.

 

[nd5y]

AMPS was abandoned but the frequencies are still used.

 

[jjbond]

AMPS was abandoned but the frequencies are still used.

Yup, thus my repurposed comment but thanks.

“As a side note, that spectrum has been chopped and repurposed already probably more than once so thus no need to hardware restrict”

 

[jjbond]

They finally pulled the plug on it in mid 2007 after several years of delay y the alarm industry.

Good read https://docs.fcc.gov/public/attachments/FCC-07-103A1.pdf

 

[jjbond]

As of 2008, the AMPS cellular providers were allowed to terminate their analog services and switch entirely to more spectrum-efficient digital services. All major cell phone providers now use this spectrum to provide services using digital technologies.

The FCC paired the 804 to 824 MHz section with the 851 to 869 MHz section of the band and allocated it for various public safety radio systems now used by police and emergency responders.

Starting on page 102 of this linked to spectrum PDF (link below image below), they go into a bit of detail about the reassignment of spectrum.



The Spectrum Handbook 2018
US Mobile Tell/Cell spectrum usage

 

[cmdcomm]

Sprint is also using the old 800MHz nextel SMR spectrum with LTE now. Its called the "Extended Cellular" Band (Band 26)

Cellular - LTE Band 5 - 869-894 (D) / 824-849 (U)
Extended Cellular - LTE Band 26 - 859–894 (D) / 814–849 (U)

 

[n1das]

For scanners, the only positive thing to come out of the cell phone radio frequency censorship under the illusion of privacy protection for uninformed cell phone users is the block forced the receiver design quality to improve...a lot. I recall my old Pro-34 handheld scanner was rendered useless for listening to (legal) non-cell phone stuff on 800MHz because the cellular images were received so strongly outside the cell bands.


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[JD21960]

Cell calls were boring* and tedious at best when you COULD hear them. I could with the Regency Handheld I had back in the 1980s.
Most all calls went like this "Hey, hows it going ... ok ..... what ya want to do? nothing. I'll come over later if you want .. no. I'm tired tonight"...SWITCH CELL, call drops. Most people *****ed about their job to a BORED listener on the other side and the call would change to another CELL mercifully for me. People have NOTHING interesting or important to say. I heard 2 or 3 calls in all the years the CELL band was open that was of any interest to me. There was no benefit to me knowing what they said either. I don't miss the CELL calls at all and I could care less what Selfie idiots do with their cancer causing phones today.

 

[slicerwizard]

For scanners, the only positive thing to come out of the cell phone radio frequency censorship under the illusion of privacy protection for uninformed cell phone users is the block forced the receiver design quality to improve...a lot. I recall my old Pro-34 handheld scanner was rendered useless for listening to (legal) non-cell phone stuff on 800MHz because the cellular images were received so strongly outside the cell bands.

All you had to do was tune to the images of the signals that you wanted to hear.

 

[n1das]

All you had to do was tune to the images of the signals that you wanted to hear.

Yep. BTDT too. I was careful to only listen to comunications that are "readily accessible to the public" (as a direct result of physical laws at work). LOL, don't listen to anything I wouldn't listen to.


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[trentbob]

I have the SRD Duo, great SDR's, you will have no problem, there is no longer a need to block out those portions as all the cellualr traffic has moved off those 800mhz frequencies and has gone to digital. There is no one there broadcasting in the clear that you could hear. They were very specific channelized frequencies with 30khz spacing.

The law is not pertaining to you having equipment tht receives those frequencies, it is spefically around "will not listen to celllular conversations"

In the early 2000's, technological change caused what no legislation could. The number of cell phones and the duration of calls had increased rapidly throughout the 90's as the cost of service decreased. Cellular systems soon were running short on available channels and also wanted to add new features like text-messaging, email, and internet access. The solution was to switch from analog FM to digital modes, which, coincidentally, could not be monitored on scanners. By 2004, approximately 80% of all cellular calls were digital. Virtually all calls are now digital except in a few rural areas. Cellular providers will no longer be required to even support analog cellular service in 2008.

Radio Scanner Guide - Part 9C: Cellular Phones and Scanner Radios

My first cellluar capable scanner was the Regency MX7000 made by AOR. I also had the 5000.. novelty at the times as they were great for Milair and I could get rid of my Bob Grove scanverter. Then I went to Pro-2004 etc.

Cell calls were boring* and tedious at best when you COULD hear them. I could with the Regency Handheld I had back in the 1980s.
Most all calls went like this "Hey, hows it going ... ok ..... what ya want to do? nothing. I'll come over later if you want .. no. I'm tired tonight"...SWITCH CELL, call drops. Most people *****ed about their job to a BORED listener on the other side and the call would change to another CELL mercifully for me. People have NOTHING interesting or important to say. I heard 2 or 3 calls in all the years the CELL band was open that was of any interest to me. There was no benefit to me knowing what they said either. I don't miss the CELL calls at all and I could care less what Selfie idiots do with their cancer causing phones today.

I remember my first RS2004 for domestic consumption. It was an easy process to open the case and cut one diode to access the 800 megahertz cellular frequencies of the day. There wasn't trunking of course but there were so few phones being used you could follow the conversations. Overall they may have been boring but I did enjoy the booty calls starting first with the call to the wife I'm working late and then the call to the girlfriend. Happened a lot LOL.

I also liked at crime scenes and big news events when the cop would say call me on the cell LOL.

 

[slicerwizard]

I did enjoy the booty calls starting first with the call to the wife I'm working late and then the call to the girlfriend. Happened a lot LOL.

I also liked at crime scenes and big news events when the cop would say call me on the cell LOL.

Yep, had both of those happen from time to time. Came in real handy when there was a scene only a few doors down the street and nothing was going out over the PD channels.

One time, while waiting for an airshow to start, had a loud talker in the crowd yakking on his phone, so I found him, then flipped to the tower side so everyone could hear the other side as well. That elicited a lot of chuckles from the masses.

Then there was the time we had a bad subway crash and the reporters on scene were relaying their stories back to HQ - and also placing cash bets on the final fatality count...

 

[jjbond]

I remember my first RS2004 for domestic consumption. It was an easy process to open the case and cut one diode to access the 800 megahertz cellular frequencies of the day. There wasn't trunking of course but there were so few phones being used you could follow the conversations. Overall they may have been boring but I did enjoy the booty calls starting first with the call to the wife I'm working late and then the call to the girlfriend. Happened a lot LOL.

I also liked at crime scenes and big news events when the cop would say call me on the cell LOL.

Yup, it was amazing how many of those "i'll be late, then BOING BZZZZZ without even changing towers, the HEY BABEYYYYY be right over" call would be next.

 

[poltergeisty]

https://forums.radioreference.com/threads/question-about-1g-2g-3g-4g-5g.386324/#post-3102786

 

[Tech1]

Would you like for people to listen to your cell phone calls ? And maybe tap into your home phone as well ?

 

[slicerwizard]

If I TX in the clear, they're more than welcome to do so.

 

[trentbob]

We are talking about a long long long time ago. Original mobile phones which used an operator in the VHF high band were clearly monitored all the time and could be heard very easily.

Portable phones in the home also could be monitored very easily just like a baby monitor could be.

Cell phone conversations can't be monitored now as simply as they were then and they were random and anonymous and often you could not hear both sides of the conversation because it wasn't a trunked radio.

No worries, it's not being done now unless a warrant is obtained.... Or is it? Hahaha.

 

[n1das]

The original BC210 scanner has a 2kHz tone detector circuit to squech the receiver when listening to an old IMTS mobile phone repeater. It was used to ignore the continuous 2kHz idle tone on the repeater when no call was in progress. It made it easy to scan 152MHz VHF and 454MHz UHF IMTS repeaters.

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[n1das]

If I TX in the clear, they're more than welcome to do so.

What slicerwizard said.

It is a mistaken notion that radio communications privacy can be achieved by making it illegal to listen and banning radio receivers that receive "prohibited" transmissions. Such beliefs are knee-jerk reactions rooted in common misconceptions regarding the physically public nature of radio. Radio listeners are not being nosey. It is the people who do the transmitting that are being exhibitionists in public. Common sense and real world experience suggests that privacy is best safeguarded by the party doing the transmitting. The courts have also held that radio transmissions are not guaranteed to be private (no implied privacy whatsoever and therefore not reasonable to expect any) and the laws of Congress will not change the laws of physics.

If I TX in the clear, people are more than welcome to listen. If I TX with encryption, they are more than welcome to try to crack the encryption. If they succeed in cracking the encryption, I want them to share with me how they did it. Then I will use stronger encryption. At no time do I expect any privacy while transmitting on the public airwaves.

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[bob550]

It is a mistaken notion that radio communications privacy can be achieved by making it illegal to listen and banning radio receivers that receive "prohibited" transmissions.

At best, that only serves as a placebo for those people transmitting. It's far easier for governments to legislate prohibitions on monitoring than it is for them to require transmitting system upgrades to make them incapable of being monitored.