Thanks Phantom!

I built a test chamber with a pressure gauge, thermocouple, and a schrader valve to let me test out the sensor board. PVC in general is NOT a good material to pressurize, especially the type that says "not for pressure", but it did ok to 40 psi. The sensors seem to be working fine.

The part of the system that I've been concerned with was the antenna circuitry; currently it has no filtering and a first pass design of the matching network. To test how good (or bad) it is I downloaded HDSDR and bought a $20 antenna to go with it. The video below shows the sensor transmitting at a distance of about 4ft from the antenna. From what I can see, I think Freescale designed a helluva RF transmitter on the chip! Even with this non-optimized proto-board signal strength is fantastic.

For test purposes I have the transmitter configured to send 16 consecutive packets... these are the pulses and beeps you see. Each packet contains pressure and temperature data measured by the chip. I plan to have the software setup where it'll take measurements every 0.5 or 1 second but only send the packets every 20 or 30 seconds in order to conserve battery power. I might even extend the transmission to 60 seconds or more... but I have yet to create a power budget. Like I said above, I want a sensor with long battery life.

Sending consecutive packets is done for redundancy; if one packet gets lost there are multiple others available and therefore the data monitoring can be consistent and continuous. When I look at the power budget and do some link testing I'll probably reduce the number of packets to 2 or 4 to, again, optimize battery life.

In addition to the above software configuration, I plan to create a comparison loop where if a significant pressure drop is detected the chip will transmit immediately and more frequently.

I've also been working on the receiver module. Next steps are to get the transmit-receive link operational and then work on incorporating the LCD display. Here's a picture from the vendor website; I think this is with the white backlight turned on.