| ??? 10/14/08 23:10 Read: times |
#159065 - how does drift impact the manpower requirement? Responding to: ???'s previous message |
Steve M. Taylor said:
Richard Erlacher said:
If it has to be handled by a technician, it could just as well be done with an op-amp Wien-bridge oscillator costing less than a dollar. Not and locking the oscillator to a fixed, but unit-unit varying frequency. Yes, I think you could automate it, but even if you can't, the DDS wallops the wien oscillator, except, just possibly in spectral purity. Steve Isn't spectral purity an issue in cases such as this? You mention drift ... Does that mean that the DDS+LVDT pair would occasionally need the attention of a technician, as it ages, or can its drift be handled with firmware? As for the unit-varying frequency ... how close to the desired frequency can one actually get with a given DDS chip? Doesn't it use a crystal reference? Given 100 ppm for the typical commercial crystal reference tolerance, how close to the desired frequency can you get? Doesn't the DDS operate in small indivisible increments? RE |
| Topic | Author | Date |
| Function Generator IC | 01/01/70 00:00 | |
| Better? | 01/01/70 00:00 | |
| Maxim | 01/01/70 00:00 | |
| Maxim unavailable | 01/01/70 00:00 | |
| DDS? | 01/01/70 00:00 | |
| Better? .5% -1% THD with discrete solution? | 01/01/70 00:00 | |
| Wein bridge? | 01/01/70 00:00 | |
| Simple wont do ... | 01/01/70 00:00 | |
| LVDT driving | 01/01/70 00:00 | |
| High performance can be simple | 01/01/70 00:00 | |
| Tuning | 01/01/70 00:00 | |
| DDS again | 01/01/70 00:00 | |
| Design. | 01/01/70 00:00 | |
| What frequency? | 01/01/70 00:00 | |
| frequency | 01/01/70 00:00 | |
| Err | 01/01/70 00:00 | |
| DDS again | 01/01/70 00:00 | |
| THD | 01/01/70 00:00 | |
| THD | 01/01/70 00:00 | |
| reference | 01/01/70 00:00 | |
| Yes, but at what cost? | 01/01/70 00:00 | |
| About 4 bucks | 01/01/70 00:00 | |
| Better? In what way? | 01/01/70 00:00 | |
| 6 dollars | 01/01/70 00:00 | |
| Gee ... That isn't so bad! | 01/01/70 00:00 | |
| Tuning | 01/01/70 00:00 | |
| Hand-tuning is not cheap! | 01/01/70 00:00 | |
| Drift | 01/01/70 00:00 | |
| how does drift impact the manpower requirement? | 01/01/70 00:00 | |
| Notes | 01/01/70 00:00 | |
| Amplitude , tempco | 01/01/70 00:00 | |
| Precision | 01/01/70 00:00 | |
| Precision ... | 01/01/70 00:00 | |
| at that rate | 01/01/70 00:00 | |
| to Steve | 01/01/70 00:00 | |
| LVDT | 01/01/70 00:00 | |
| power/energy meter IC | 01/01/70 00:00 | |
energy meter IC | 01/01/70 00:00 | |
| at that rate | 01/01/70 00:00 | |
| Filtering? | 01/01/70 00:00 | |
| It will remove SOME of the distortion | 01/01/70 00:00 | |
| have you seen this? | 01/01/70 00:00 | |
| I am afraid | 01/01/70 00:00 | |
| Simple` | 01/01/70 00:00 | |
| DTMF Genarator | 01/01/70 00:00 |