final acceptance test of FCC requirements in production floor
We tested our product in RF testing Lab and got FCC certfication and FCC ID.
Are there any requirements for RF acceptance tests during production?How could I be sure that the device I've tested in external lab now doesn't not exceed FCC limits in mass production.
Thanks
An interesting question. You are, de-facto, certifying that equipment you build meets the requirements, and that you have not made any major changes to it since certification. And some major changes might not be so big, such as changing the resistor value on the output power amplifier bias network!
On the other hand, especially for consumer goods, too much testing is not possible with the low sales price.
I would concentrate on important parameters. If it is a transmitting device, I would check frequency accuracy and transmit power as a minimum. That way you are not selling product that is way out-of-band for frequency or blasting too much transmit power. Frequency is easy, just check on either spectrum analyzer or a frequency counter (may have to program it to go into a CW tone test mode). Alternately you could just check the Crystal freq. reference and make sure it is at right frequency +/- tolerance in ppm.
Transmit power is a little harder. If you can disconnect the antenna...you can put a power meter or a spectrum analyzer there. If the antenna is permanently attached, you need to make some sort of highly repeatable test fixture to put the unit in, with a built-in test antenna.
If there are other important parameters...you might want to add them too. Often a "golden unit" is used nearby to make sure your transmitter talks to it properly.
Of course, if you want to spend serious money, there are complete VSA mimo test solutions available for just about any modulation!
Thanks Biff,
That're exactly the minimum tests we do today.
Do you know if It's sufficient for FCC or CE?
I am not aware of any specifications from exactly what you need to test. Someone jump in here if they do know of a list of required or recommended tests.
You are "guaranteeing" that the unit works within the specifications when it is shipped. You need to set up a series of tests to show that. But you do not have to test 100% of the units. There is a fair amount of work done, especially in military products, that answer the question "how often and what parameters need to be tested thoroughly". Semiconductor manufacturers have this down to a science, and track various parameters that tell them if a device is "losing its recipe", but statistically know what parameters to stop testing because they are not good indicators of anything.
You could start off here:
http://www.barringer1.com/mil_files/MIL-HDBK-H108.pdf