| ??? 01/06/05 15:58 Read: times |
#84464 - Run the numbers Responding to: ???'s previous message |
Before you agonize too much over the precision of your 40kHz
signal, you may want to test your devices. My experience: I bought a small batch of (cheapo surplus) 24kHz transducers, whose specs said (apx.) "Center frequency: 24kHz (+/-5%)". I took this to mean the Center Frequency was exactly 24kHz, and the response "tails" were 5% in either direction. After some head-pounding over my results, my (much wiser) brother pointed out that this actually means that the Center itself might vary up to 5% either way from 24kHz. Sure enough, after running the numbers it turned out their highest output was at (IIRC) 24.86kHz (+3.5%); at exactly 24kHz, there was barely a murmur, and at 24kHz-epsilon there was nothing at all. I imagine (hope) that the $35 transducers are spec-ed a bit more tightly than the $1 ones, so maybe this is what I get for being cheap, er, "frugal" (:-)). |
| Topic | Author | Date |
| how can i do a40kHz signal for 10 cycles | 01/01/70 00:00 | |
| whole numbers | 01/01/70 00:00 | |
| baud rates | 01/01/70 00:00 | |
| CAN baud rate | 01/01/70 00:00 | |
| Tutorials and the Bible | 01/01/70 00:00 | |
| reply | 01/01/70 00:00 | |
| Thanks for the advice | 01/01/70 00:00 | |
| Actually... | 01/01/70 00:00 | |
| And what about 2x Xtal? | 01/01/70 00:00 | |
| 40Khz for 10 cycles | 01/01/70 00:00 | |
| Run the numbers | 01/01/70 00:00 | |
or | 01/01/70 00:00 | |
| Don't forget | 01/01/70 00:00 | |
| Resonance | 01/01/70 00:00 | |
| 12MHz would not work, either | 01/01/70 00:00 | |
| 22.118MHz for signal and CAN | 01/01/70 00:00 | |
| CAN CAN | 01/01/70 00:00 | |
| CAN and 'CC02 | 01/01/70 00:00 | |
| some correction | 01/01/70 00:00 | |
| Get 40,000 kHz T2 auto reload 12 mHz | 01/01/70 00:00 | |
| sounds like an application for a PCA | 01/01/70 00:00 | |
| ... and this IS an RD2 | 01/01/70 00:00 |