Get signal strength

Hi,

I am building my remote control using 433Mhz RF to control my quadcopter. I am studying ways to make the range better but I would like to know if there is someway I can check the signal strength.

I want to compare how different antennas improve my range, so I would like to know the strength of the differenet models of antennas at 1 metter, 10 metters... and choose the best. I use the commonly used fs1000a 433 MHz module to transmit and receive data. Anyway I can check signal strength with arduino?

Nope. That device only returns 0/1 data at the output port. Need special RF equipment. Best for you is to equip a receiver and have it display a test message as you walk away from the transmitter, see where the messages stop coming in. Higher voltage at the Tx will work better than lower voltage in general. Do you have a data sheet on it?

Another option would be go to 2.4 GHz and nrf24L01+ transceiver. Then quad copter can send you an ACK back everytime it gets a message. Use the version with pre-amp and whip antenna. http://yourduino.com/sunshop2/index.php?l=product_list&c=12

Can also review the datasheet, see if it has signal strength reporting.

http://arduino-info.wikispaces.com/Nrf24L01-2.4GHz-HowTo

http://www.nordicsemi.com/eng/content/download/2726/34069/file/nRF24L01P_Product_Specification_1_0.pdf

Looks like it does - question then becomes do the existing libraries support that, or do you need to code something up?

6.4 Received Power Detector measurements Received Power Detector (RPD), located in register 09, bit 0, triggers at received power levels above -64 dBm that are present in the RF channel you receive on. If the received power is less than -64 dBm, RDP = 0. The RPD can be read out at any time while nRF24L01+ is in receive mode. This offers a snapshot of the current received power level in the channel. The RPD status is latched when a valid packet is received which then indicates signal strength from your own transmitter. If no packets are received the RPD is latched at the end of a receive period as a result of host MCU setting CE low or RX time out controlled by Enhanced ShockBurst™. The status of RPD is correct when RX mode is enabled and after a wait time of Tstby2a +Tdelay_AGC= 130us + 40us. The RX gain varies over temperature which means that the RPD threshold also varies over temperature. The RPD threshold value is reduced by - 5dB at T = -40°C and increased by + 5dB at 85°C.

Page 26 of the datasheet:

6.5 PA control The PA (Power Amplifier) control is used to set the output power from the nRF24L01+ power amplifier. In TX mode PA control has four programmable steps, see Table 17.

It varies in 6dB steps from -18dBm (16uW) to 0dBm (1mW). Since the power received is merely a go/no go, you could step the transmitter power and see where it changes to get a bit better idea when you are getting close to the limit.