How Many Radios in Your Home?

How many radios do you have in your home? If you live in a developed country you’d probably be surprised. I managed 20. Can you find more?

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How many radios do you have in your home? If you live in a developed country you’d probably be surprised. The word ‘radio’ brings to mind old-fashioned radio receivers for listening to pop music, but there are radio transmitters and receivers hidden away in so many other items we take for granted these days. Out of interest I decided to do a quick count round my own rather small house to see how many I would tot up.

Note that for the purposes of this survey I counted all radios, whether they were receivers, transmitters or both (sometimes called transceivers).

Starting with radio broadcast receivers I count three: my bedside radio alarm clock, my portable radio in the kitchen and the radio built into the hi-fi in my living room. Since I’m only counting items in the home, I’ll ignore the radio in my car as it’s parked on the street.

So far, so obvious.

Now mobile phones are basically radio transceivers (how else did you think they communicate with the basestations?), so I suppose I should count these as well. And I have two mobile phones, to boot. But here it gets tricky. Most modern mobile phones actually have several radios in them: separate radios for each different radio technology they can use. My most basic phone is GSM (2G) only, so that’s one. My smartphone has GSM and UMTS (3G), plus Bluetooth, wi-fi, and a GPS receiver for location-based applications – five radios in one device!

OK, so I’m up to nine now.

Whilst I’m rooting about in my pockets I come across my car key. It has remote locking/unlocking, so guess what – that’s another radio. And thinking of car keys, the spare set hanging up brings the total to 11.

Looking over at my laptop I’m reminded that it has wireless internet over wi-fi, so I need to count the wi-fi transceiver that’s built into it. The other end of the link is the wi-fi broadband router sitting in the corner of my living room, so that makes another, bring my total to 13 so far. Mmmm, that’s an unlucky number, so I’d best find more pronto!
 

I can’t count any more computers as I only have one in the house. (What sort of electronic engineer am I with only one computer? In my defence, my wife took the other two when she left!). Nor do I have wireless-connected scanners or printers or keyboards or mice, so no more radios to be found there.
Salvation from the unlucky 13 comes when I remember that TVs are basically radio receivers, just that they receive radio signals which happen to be carrying pictures rather than audio. So I can count the digital TV in the living room for 14. The old analogue TV in the bedroom also has a digibox to receive digital TV signals, so that’s two more, bring me to 16.

Can I find any more? I don’t have satellite TV. But suddenly I remember I have an old GPS receiver at the back of a cupboard, which I used to carry when out hiking, back before I got a mobile phone with GPS built in. I go to check I really still do have it, and notice a pair of walkie-talkies I bought years ago (PMR446 band, to be specific). And beside them an old video cassette recorder. The VCR has an analogue TV receiver in it, so that counts too. The contents of that cupboard add another four to my total.

Another quick scout around the house doesn’t reveal any more. I don’t have a wireless door bell. Nor a remotely opening garage door (for the simple reason that I don’t have a garage!). The remote controls for the TV, DVD player and hi-fi don’t count because they communicate using infra-red, not radio waves (yes, I know radio waves and IR are both part of the electromagnetic spectrum, but I’m not going to stretch my definition of radios quite that far).

So I’m stuck at 20. I could, at a pinch, try to claim the microwave oven is a radio transmitter since it cooks by heating food with radio waves at around 2.4 GHz, the same frequency band as wi-fi (and I counted the wi-fi radios, after all). But it’s not a radio in the sense that it’s not transmitting or receiving radio waves carrying information, just raw power for heating, and it’s not a conventional transmitter since it is enclosed and not sending the radio waves out beyond its own confines (just as well, or it’d cook me too!). I decide not to count it either.

20 radios it is, then. Can you do better?

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This article was first posted on Triond, here.