how can i connect a relay device?

[ceyhunkirimli]

Hi everybody,

I am a PhD student in Biomedical Engineering Department, in Drexel University. My advisor decided to buy one of the analyzers (aim 4170c) We are planning to scan the impedance spectrum of a sensor we developed in our lab with the device, however we want to use a relay device that will switch automatically between 4 different sensors. My question is we want to have a full scan between 2 frequencies for each sensor and when the scan finished aim 4170 should send a signal to the computer so that laptop can send a signal to the relay to switch to the second sensor for the same full scan, and so on, until the full scan of the fourth sensor has been made. Is this possible? can we control the analyser by labview or some other software so that we can write our own routine in that language (matlab, labview, java etc.?) thanks for your attention, i hope i made the problem clear to you...Hope to hear from you soon,

Ceyhun

[Bob]

Hello Ceyhun,

The AIM4170C can be integrated with a measurement system that is programmed by the user. The system program can be written in any language and the communication with the AIM uses a simple system of flags. There are accessory boards for driving relays which can be plugged into a computer. The AIM program and the master system control program can run at the same time on the same PC. There are details about "External Control" in Appendix 10 of the AIM4170C manual.

Best regards,
Bob - W5BIG

[w0qe]

Ceyhun,

Please take these comments as being constructive since your background is not RF engineering. Before you can talk about making measurements and building switching circuits consider the following:

1.) What frequency range will you be scanning the sensors?
2.) What is the expected impedance of the sensors over the selected frequency range?
3.) What power level do you need to scan the sensors?
4.) What accuracy is needed from the measurements?

The 4170 scans at a power level of about -18 to -22 dBm and is not adjustable. Making test fixtures in the KHz region is different from the 100+MHz region. The problem is definitely compounded if the expected impedance is very high or very low (question #2). Making an RF impedance of 1 ohm at 100 MHz with a 5% accuracy is extremely hard to do.

How many sensor measurements are you really going to make? Is automating the testing procedure part of the project or is it really required due to the quantity of measurements you need to make? The problem as you stated it is pretty open ended which might discourage responses. Post some more details and you might get some good ideas.

Larry, W0QE