Don't Try This At Home? 

This sounds like the audio I heard, while aboard ship in the USN 40 years ago. I was told at the time it was encrypted audio that we did not have the key to decrypt. It was a radio transmission from a aircraft.

Could be useful when the space aliens come to take over the earth.

Before the American police departments switched to P-25 encrypted digital, they would use this scrambling technique with a black box attached to their FM transceivers. They would be given a code instruction to dial in by dispatch, and then talk about a secret message. Sometimes it was about a homicide, or when a drug raid was to begin. After the event they would switch back to regular transmissions. This was when the police trusted the public and appreciated the help of the listening public to call in and help when they were looking for a particular person or car. Nowadays they digitally scramble every call. What happened to their trust ?

Good info! Thanks

That dummy load antenna has a considerable radiator element. I suggest adding a reflector and a few directors to it.

Simple audio inversion, which is essentially lower sideband audio. A fixed audio tone in the 1000 to 2000 Hz range is mixed with the audio and the difference is used, then the tone re-injected on the RX side. This is voice privacy at the lowest level. About 30 years ago, while still in the analog domain, companies like Midian and others came out with rolling code inversion that was virtually impossible to decode, which changed the injection tone hundreds or thousands of times a second, with everything synched on the keydown. The only problem was you couldn't come in mid-transmission. DVP, then DES, then AES came after. Best ENC is military-only frequency hopping. As for using it, if you are deliberately trying to obscure a message's meaning then it runs afoul of Part 97. I recall one P25 repeater owner published his AES key on the repeater's website or anybody to try it out as an experiment. There was also a voice message transmitted at ID intervals instructing the curious where to find the ENC key for it.

To scramble or not to scramble, that's exactly how people sound to me anyway, when I'm tuning them out, tnx Man!

One of my favourite inversion-scrambling stories came out of Toronto in the mid-90s. There were two traffic reporters in Cessna 172s who would fly around the city during rush hours. The news desk used Motorola Virtual Privacy Adapters for breaking stories to reporters, and the airplanes had it as well. One of the two retired pilots was a serious radio gearhead and one day, killing time live on air (this was a 50kW directional AMer on 680 kHz) he was giving his report and said something along the lines of "I wonder if I can fly upside down to see the traffic better. Here we go, turning, steeper, steeper, almost there [flips on the scrambler] I'm upside down now (or probably words to that affect, then back to clear). The studio announcer was utterly dumbfounded and the back channel chatter on 150 MHz was....interesting afterwards. I had a similar box on my commercial radio that I used with some news junkies on a legal business band simplex channel and we'd listen in on them and got all the news scoops until they wised up and went to rolling code.

Excellent post-SHTF feature.

Thanks Steve, no one has shown scramble mode before... that I've seen anyway. My uhf cb has them. I bought a uniden set in 2010 but never used scramble but probably should have. ;)

Whether or not it's a 'successful' attempt at encryption the FCC rules and regs stipulate that we cannot transmit "...messages encoded for the purpose of obscuring their meaning, except as otherwise provided herein... " - Part 97.113-4 "For the purpose of obscuring..." doesn't leave any wiggle room at all, since however simple-minded and easy to crack this scrambling system is, its 'purpose' is perfectly clear. It's a scrambler. It's illegal in the USA.

Sounds like frequency inversion (aka USB->LSB or in reverse). I built a scrambler/descrambler way back using a series of BPF/LPF filters and a mixer. See if a UHF rig with LSB/USB can’t descramble these.

yeah it is true that we have a license to experiment with, but in many people's eye this can be interpreted as encryption and therefore in the radioamateur world it is legal for us to use.

Scrambling is illegal on amateur radio, GMRS, FRS, MURS. Encryption is also illegal. Scramble is generally pretty easy to decrypt. Encryption is harder, but still easy enough with enough computing power. As you said, once you transmit, it will be easy to identify and track. Why not use DMR or another digital mode on ham radio, which is legal and much harder to decrypt with an FM radio?

🤣 Not illegal in AU ..voice inversion is a standard in UHF CB radio's Uniden & Icom, RTTY does a decent job deciphering inversion. What is Illegal is real encryption !

So if you have a couple of these radios set to the same scramble mode you can talk to each other?

Weird because I have worked in a department that had encryption and well that was just weird

This is just inversion scrambling. Fairly easy to decode off you need to. It's not illegal on Amateur radio and as you said, it's definitely not any form of encryption.

I wanted to what the scrabbled audio sounded after being "decoded" Not just when the scrabble was turned off. On another topic. Who makes a radio with PTT-ID decode ? Many have PTT-ID encode ?

Does this radio transmit outside the amateu....um, normal...um, expected...um..... Have the transmit frequencies been hacked?

I will first say that this Baocraps are most likely FCC type accepted for Part 90 [however I take that with a grain of salt]. Scrambling is legal in Part 90 radios and type is up to the licbese holder. Next, a difference exists between encoding and encryption and they are not the same. Encoding is using a form of communication (i.e. P25, DMR, Fusion, Tetra) where encryption is a means to secure a communication within the form. Just because someone does not have a radio or a scanner that they can listen to does not mean it is encrytped. [FYI receivers or scanners exist for all digital voice modes]. Finally, it is illegal to scramble or encrypt anything in the US amateur band except for Communications to control a space station [remember it was a test question]. Even if you publish a code, the key, yada yada yada it is illegal. This was a hot topic of those being branded with Motorola back in the early 2000's and the FCC said no. Icom did not even allow the US version of the V82 to take the ut-114 encryption chip cause it is illegal. Even the Yaesu FT-4x Us version does not have the encryption firmware. However, other versions in the world that allow does have it. This encryption is also standard voice inversion which mixes an audiable tone with your voice to invest the audio. The tones can range (on some radios) from 300 Hz all the way up to 3000 hz and everything in between. High and more secure tone inversion modes exist like rolling code/hopping code which chnages the tone each keyup or hops tones during transmit. The standard voice inversion can be decoded in less than a minute with either computer software or even a SSB radio. Steve the biggest question is are you going to have to pay $10,000 total for illegal transmissions or $30,000 for x3 @ $10,000 😂. Ban the Bao's in 2024!

Im looking in Part 97. It clearing prohibits scrambling your signal. I think.

I have two radios that have scramble mode, I really don’t understand any reason why, I want to be heard and clearly understood when I transmit.

so if it does turn out to be JUST audio shifting... it would be TECHNICALLY fcc compliant for HAMs to use?

What is that absolute beast of a dummy load? Can you provide a link?

Years ago I got a pair of UHF handies that used frequency-hopping spread spectrum. Not on a ham band and no license required. Does anyone know if they are legal? Not encrypted but pretty hard to make sense of. except with a very agile receiver like the FCC and CIA probably have.

Quite simply, this is not encryption and is not an FCC violation. Good to go. IMH Amateur opinion.

Why would anyone need this anyway? Even drug dealers wouldn't bother with it, they haven't yet...

Speech inversion. My local sheriff’s department occasionally used it. I built a descrambler before this was made illegal.

Regardless of its legality, I think this "scramble mode" is of little use, as anyone with a compatible HT has 3 chances of finding you. As a radio amateur, you can experiment as much as you want, if you respect the bandwidth and power limits. 73!

You sound like the alien voice-over in the movie Hangar 18.

You didn’t explain how the receiving radio descrambles the audio -- you didn’t do a demonstration of that

at least in Europe encryption in amareur radio is not allowed

FYI: This mode of scrambling is called frequency inversion.

corect me if I am wrong, that is analog voice inversion.

You could also transmit with minimum power necessary, keep transmissions as short as possible and frequently change frequencies to legally remain hidden.

UK Ham Licence specifically prohibits encryption, so not legal here. I don't really see the point, I want people to hear me, and if I want private I use a cell phone.

Not illegal as NSA and GCHQ has all the codes to decrypt.

Technically encryption is illegal on the ham bands. However, DSTAR and C4FH are forms of encryption and the FCC allows them to be used. These two digital voice modes cannot be de coded without the proper digital chip so it's a bit strange that the FCC turns a blind eye to it.

Really. I don't see or hear any difference between the 3 scramble modes.If it's legal, guess what?F c c approved it so we can do it

The scramble mode is illegal. The FCC should remove these products from the market.

nice dummy load. not Shure if how legal that is. I have it on a GMRS radio. never used it. this was used before P-25 was used. 73's

yes

Freedom is a dangerous thing. If we live in free democracies, we should be able to light encrypt to the extent that the state can decrypt in case of abuse for bad purposes. What is emphasized here is not encryption, it belongs more in the area of ​​coding.

Did I hear right - it made you sound like you were talking in Chinese ?

Sad Ham

I don’t think that’s “legal” . . “encoded for the purpose of obscuring their meaning”

Amateurs 😒

While I personally don't care, it's not legal, as you cannot legally transmit encrypted to obscure the signal per § 97.309 (4)(b). I'm not going to do it, but I think this is a tiny issue. Most hams won't use it.

Why all the hullabaloo about something that is a COMPLETE non issue, are there no more radio topics left in the world, that we are wasting time on this all over the interwebs??? IT is perfectly LEGAL, and anybody with nose trouble that wants to listen to my or your conversation just needs to put the effort into buying the matching radio, and fiddling with the settings on his shiny new outta the box radio until he can once again eavesdrop happily again!!!

This is not encryption. Anyone stating such is being disingenuous.