Direct I/Q demodulation

[scrungy_doolittle]

The scheme I posted does not make this assumption. You can take as long as you need to process, and you signal that you are ready to accept more samples using flag when you done. When display needs to be updated processing can take a while...

Using double buffer is a good idea. Concurrent sample acquisition using ADC->DMA and processing previous samples with CPU will almost double data throughput. The CPU processed buffer can't be updated by ADC->DMA; logic for it can be handled in the IRQ handler (looking a the acqDone flag.. and pointing DMA for the next cycle to correct DMA buffer) This sometimes called ping-pong buffering. The flag signaling is not needed if you can guarantee that you can always finish processing before buffer switch, but unless you have another CPU to do user interaction that can't be the case.

The problem with this, is that while you "taking as long as you need to" to process, you will be missing segments of ground due to the detector scanning motion.
A MEMS accelerometer, down at the end of the shaft (not on the head), can provide swing information to allow you to alter your processing level based on the speed of the swing.

What I think would be really cool, is to develop an acquisition system, that transmits the digitized data directly to a tablet over a fast wireless link and put all the smarts and processing in an app that runs on your smart phone. the detector circuitry wold be very small, the batteries would be bigger, but this would allow you to bring a huge amount of signal processing to bear on the issues. After all a 1 ghz arm, even running java, is pretty fast incomparison to pics, STM's and arduinos.

[scrungy_doolittle]

The scheme I posted does not make this assumption. You can take as long as you need to process, and you signal that you are ready to accept more samples using flag when you done. When display needs to be updated processing can take a while...
Using double buffer is a good idea. Concurrent sample acquisition using ADC->DMA and processing previous samples with CPU will almost double data throughput. The CPU processed buffer can't be updated by ADC->DMA; logic for it can be handled in the IRQ handler (looking a the acqDone flag.. and pointing DMA for the next cycle to correct DMA buffer) This sometimes called ping-pong buffering. The flag signaling is not needed if you can guarantee that you can always finish processing before buffer switch, but unless you have another CPU to do user interaction that can't be the case.

Well, if you are careful to put the majority of the buffer switching and processing into background interrupt driven, or hardware controlled code, and do the UI in the main loop you can.

[Daren]

Well, if you are careful to put the majority of the buffer switching and processing into background interrupt driven, or hardware controlled code, and do the UI in the main loop you can.

Yeah, that will work

[moodz]

The problem with this, is that while you "taking as long as you need to" to process, you will be missing segments of ground due to the detector scanning motion.
A MEMS accelerometer, down at the end of the shaft (not on the head), can provide swing information to allow you to alter your processing level based on the speed of the swing.

What I think would be really cool, is to develop an acquisition system, that transmits the digitized data directly to a tablet over a fast wireless link and put all the smarts and processing in an app that runs on your smart phone. the detector circuitry wold be very small, the batteries would be bigger, but this would allow you to bring a huge amount of signal processing to bear on the issues. After all a 1 ghz arm, even running java, is pretty fast incomparison to pics, STM's and arduinos.

Yup ... the wireless app is exactly what i do ... see MAGPI app in android store ;-) ...the detector is just a black box ... although i have considered other colors too LOL.

[scrungy_doolittle]

Yup ... the wireless app is exactly what i do ... see MAGPI app in android store ;-) ...the detector is just a black box ... although i have considered other colors too LOL.

chuckle. I shall look at MAGPI in the android store. Did you write the app yourself? It looks lovely. drop me a pm....