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Tuesday, 17 December 2013

What is CTCSS and DCS?

CTCSS and DCS are systems used to ignore other users who you may be sharing a radio channel with. These two systems are also referred to by other names, including CDCSS, PL and DPL, but the official terms are CTCSS and DCS.  They both have the same function and work in similar ways.

CTCSS stands for Continuous Tone Coded Squelch System. Basically what it does is this: it adds a tone into your transmission at a certain frequency. Other radios must have the same CTCSS tone or code set to hear the transmission. It will also be heard if the radio has CTCSS and DCS off.

Different CTCSS codes have different frequencies, and this is how it filters out other people - as long as they have a different CTCSS, or no CTCSS, then your radio will not pass any audio to the speaker. A radio with CTCSS enabled will only pass audio for the tone it has set.

DCS works the same, apart from it being digital instead. It stands for Digitally Coded Squelch. It sends a number repeatedly encoded in digital as you speak, in the low frequencies so you do not hear it. If someone else transmits on the channel with a different or no DCS, the radio will not unmute. If they transmit with the same DCS as you, then your radio will unmute. DCS is newer than CTCSS, and has more codes. This gives a lower chance of picking the same code as someone else.

Now that you understand how these work, I also want to clear something up. Some manufacturers call them "Privacy tones" or Privacy codes" or even act like they are different channels, and advertise that the radio has "968 channel combinations."  All of this is completely untrue.  CTCSS and DCS don't stop anyone from listening to you, they just stop you from hearing other people. If someone has a radio with no CTCSS and DCS on, they will be able to hear everyone on the channel/frequency, including people using CTCSS and DCS.

CTCSS and DCS do not make additional channels. If someone is on the same channel with a different code, then it's not a different channel. If you stand next to them and both transmit, your radios will interfere because they will still be trying to use the same channel at the same time. On PMR446, there are only 8 channels (or 16 channels in new radios after the law was changed to allow 8 new channels), and no CTCSS or DCS can change that. The same with FRS, GMRS or any other radio band.

How to choose two way radios

This post will be about how to choose two way radios. It is about two way radios for private use, or personal use, not business radio.
When choosing two way radios for personal use, you will be choosing from a few categories. If you're in Europe, there is a market of PMR446 radios to choose from. In the US, you can choose from a range of FRS radios, or GMRS if you get a license.

Friday, 13 December 2013

Motorola DP3400 TRBO radio review

I recently bought 2 DP3400s and have been enjoying using them. I have to say that immediately you can tell that they are better quality than the Kirisun S780, but you would expect that when they cost about 4x as much.
The radios feel sturdy in the hand, and they feel like they wouldn't break easily if dropped. They are also submersible in water which is a very handy feature. I haven't dared to test this yet, but I have put the radio under a running tap, and it survived that test perfectly well. On the downside, the radio is incredibly heavy compared to any other radio I have ever owned (about 400g). It's almost double the weight of the Kirisun, and a lot more than my other radios. This is down to the battery, which is very heavy - the actual body of the radio is quite light without the battery. I think it's a shame that Motorola only supply the radio with a NiMH battery, whereas most radios these days come with the superior Li-Ion batteries.

The analog audio sounds very nice on transmit, although it could be a tiny bit louder. (Even with the gain turned right up)  The digital audio sounds very nice too, I think it sounds a lot better than the Kirisun's, and it also has a much longer range than them. The range of the digital using these radios is more or less the same as analog, when used without encryption. However, the range does decrease quite a bit if you turn on enhanced privacy, so I would not recommend using enhanced privacy. Digital definitely sounds an awful lot better than analog when the signal is bad, however, I think analog sounds very slightly better when the signal is good. This is only true when the signal is so strong that there is no noise.

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