Receiver Power Usage

Wireless & IoT
1

Hi everyone, does a wireless receiver use us much power/current when sitting waiting for the transmitter to transmit a signal? If I had a battery operated receiver (like those 315khz one on this site), would I be able to keep it running for weeks without sending it a signal??

Thanks,

Denis.

2

In general a receiver consumes a constant power regardless if it is receiving a signal or not.

You can check the data sheet to see if there is a spec for receiving a signal verse not or you can measure this yourself.

3

brainwav:
Hi everyone, does a wireless receiver use us much power/current when sitting waiting for the transmitter to transmit a signal? If I had a battery operated receiver (like those 315khz one on this site), would I be able to keep it running for weeks without sending it a signal??

Thanks,

Denis.

Depends greatly on what kind of wireless.

Some transceivers use the same power whether transmitting or receiving. Example: XBee

Some use more while transmitting (higher power modules). Example: XBee Pro

Many other examples.

Battery powered devices with transceivers usually have a sleeping strategy so the receiver is off a high percentage of time. Example: modes/options in the XBee and the HopeRF RFMxx modules and clones.

Yes, you can run for weeks IF you design it to turn off the receiver at least 90% of the time. You can do the math, given receiver current consumption versus various batteries’ mAH rating.

If the other end of the radio link is always-on (mains powered), this is easy.

If both are battery powered, there are popular schemes to have the two units wake up at the same time. This is called time-synchronized rendezvous.

4

More advanced devices intended for low-power operation have a power-down feature. Have a look at the nRF24L01+.

5

and the sub-GHz (433/868/915MHz) modules based on the SI Labs chips - these too have a low power sleep mode.

Used in modules from HopeRF, like their RFM12, RFM22, etc. SparkFun sells one of HopeRF’s modules; another seller is moderndevice.com, jeenode modules.

Also, Microchip uses one of the SI Labs chips and marks it with Microchip’s logo and part no. 4421, but I haven’t seen these in a ready to use module as above.

I’ve been using the jeenode modules in 915MHz.