# How to get frequency of Angelcare baby monitor?

Angelcare baby monitor is a device, which is monitoring if the baby is breathing and whether the noise level is above some level. This information is sent to the wireless device. I want to show this information elsewhere on my web, so I was thinking about extracting it from data emitted by baby monitor.

My question is, is there any possibility how to get the frequency that baby monitor is using?

UPDATE1: It's AC403-D (D stands for german market). I read in manual Transmission from the Nursery Unit to the Parent Unit is made on the 864 MHz frequency in Europe. So if I use Channel 7, I cannot say which frequency is that either way, right?

• Can't you forward the information from the receiver? – Bence Kaulics Sep 1 '16 at 11:28
• A link to the actual device would be useful. Only knowing at what frequency it transmits is pretty useless, you need to know what protocol it uses as well. If the device can also relay sound and is from the last 10 years, chances are it uses DECT which is encrypted so you will have no chance of capturing anything usefull. – Bimpelrekkie Sep 1 '16 at 11:35
• Angelcare seems to be using the 2.4GHz ISM band. They also mention automatically changing channels to reduce interference. So, probably not a single frequency that you could easily monitor. Might be bluetooth, might be similar to wifi, might be altogether propretary, so not much chanceof you getting data out of the radio signal. You'll probably do better to get the needed info from the receiver. Or, just make your own noise detecting device and post that. Or just, you know, not post your baby's private life on the internet. – JRE Sep 1 '16 at 11:39
• OK. With the model number given, it isn't 2.5GHz and you can select channels manually. The channel frequency can be measured, but you still don't have any way to interpret the data being sent. There seems to be quite a bit of stuff that it sends. – JRE Sep 1 '16 at 13:03
• If you had an oscilloscope, could you use its FFT on the antenna? – Bort Sep 1 '16 at 14:15

This is a intentional radiator. That means, in the US at least, a FCC certification number must be available on the package somewhere. Look up that number to get the details of what frequency and power the transmitter is permitted to use.

I expect there is a similar mechanism in other jurisdictions.

• Same in Europe and countries that follow the European R&TTE/RED directives: intentional radiators have to provide plain text information (through a label or through written instructions delivered together with the product) stating which band they operate on and what power they transmit with. – Lundin Sep 1 '16 at 11:45
• It's 864 Mhz, see my updated question. Is it possible to find out which frequency is that, when using channel 7? – Mej Sep 1 '16 at 12:30
• @Mej: Possibly there are standard "channels" in a narrow band around 864 MHz, but this could be something the manufacturer picked themselves. I'm not familiar with specific usage of that band, particularly in Europe. It could even be that different channels use the same spread frequency, although that implies complexity unlikely for a simple device like a baby monitor. – Olin Lathrop Sep 1 '16 at 12:46

In Europe, 864 MHz is a license-free, harmonized band, regulated by EU Decision 2006/771/EC plus some amendment 2013/752/EU.

Looking at the first of those documents, the band was apparently originally reserved for wireless audio with maximum power 10mW e.r.p which sounds to be the right kind of application.

In the second document, they also opened up the same band for "non-specific short range devices", given that they follow the rules of radio compliance (ETSI standard 300 220). Much like the open 868MHz band.

No channel spacing is specified for the band, so we can't really know how wide one channel of your specific device is. It could be wide band FM audio, or it could be some narrow band signal with a digital protocol, etc etc.

It is however unlikely that they use some sort of frequency hopping, so you should be able to determine the frequency and channel width used with any simple spectrum analyser.