How to measure the receiver sensitivity?

[Andrea]

Which is the simplest way (without special instrumentation if possible) to measure the sensitivity of a receiver? I'm talking about a data receiver around 400Mhz for example.

Is there any standard or procedure about receiver sensitivity measurements?

Thanks

 

[Borber]

Re: Receiver sensitivity

You can not measure receiver sensitivity without modulated signal generator at input signal frequency and level meter to measure signal/noise ratio or BER of output, demodulated signal. Kind of instruments depends on type of modulation you are using.

 

[Andrea]

Re: Receiver sensitivity

Thank you for your answer.

Let's say we need to test a pager receiver. We have a transmitter and encoder. We could send data patterns from a PC and measure BER with a PC connected to the receiver. Can we do some rough testing without other instruments?

Is there any document, standard or specification related to pager receiver testing?

Thanks.

 

[Borber]

Re: Receiver sensitivity

What you need besides transmitter, encoder and BER software is step attenuator (10dB and 1dB) between transmitter and receiver connectors. Output power of transmitter must be known.
In case of build-in receiver antenna things are different. You will need transmitting antenna of known gain and in some distance calculate field strength at receiver. If receiving antenna gain is known you calculate power of received signal.
In all cases you must adjust output power to such level that corresponds desired BER.

 

[VSWR]

Re: Receiver sensitivity

It depends on what you mean with 'sensitivity'. You can simply increase the distance between between the transmitter and receiver until the data link drops or you reach 'out of range'. This might be a coarse test of sensitivity as you then may judge if the cover range is sufficient or not for your specific need.

Of course there are several contributions of the max available range transmitter-to-receiver. RX sensitivity is only one factor. Others are TX output power, TX antenna gain, RX antenna gain, buildings in the signal path, RX intermodulation due to strong nearby transmitters, etc.

 

[toooo]

Re: Receiver sensitivity

You can measure the noise figure of the receiver and use the sensitivity eqution to caculate the sensitivity.

 

[Rayengine]

Re: Receiver sensitivity

Thank you for your answer.

Let's say we need to test a pager receiver. We have a transmitter and encoder. We could send data patterns from a PC and measure BER with a PC connected to the receiver. Can we do some rough testing without other instruments?

Is there any document, standard or specification related to pager receiver testing?

Thanks.

For pager sensitivity, it goes very simple techniques. Put the pager in TEM cell, adjust the power level feeding in the TEM cells until the pager unit doesn't "sound" is the sensitivity.

 

[springf2000]

Re: Receiver sensitivity

the simplest way is to use the signal source to input your receiver,then adjust the output power of the signal source enough small so that your receiver can just can demodulate the data,the signal source output power is your sensivity

 

[Andrea]

Re: Receiver sensitivity

Can anybody give me some more information abou TEM cells? Is there any useful link on the net?

Thanks