Re: [time-nuts] What's available in the way of DSP for new WWVB?
One of the problems with the iMX RT series, is that any processor below the 1064 (Teensy 4.0 and 4.1 use 1062) do not have any internal FLASH. It is all external in a separate FLASH chip sitting out there waiting to be read by your competitors. So, the iMXRT has a bunch of boot time complexity, optional encryption, and bootloader memory movement options you have to manage to boot the device. Typical for machines designed to run big OS's, but not normally seen in microprocessors. Paul Soffrigen, of PJRC, says that some of his bigger customers did not want the ARM SWD exposed, because they thought it would make it easier for competitors to read their object code. Yes, if you tell MCUXpresso to generate a ".hex" file, you can load it with PJRC's separate executable. But I would rather hook a Segger directly to the target. Thanks for the tip about TyQT, I did not know about those tools. --- Graham > > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
On 10/16/20 1:54 PM, jimlux wrote: On 10/16/20 9:08 AM, Graham / KE9H wrote: On Tue, Oct 13, 2020 at 12:19 PM paul swed wrote: Graham take a look earlier in the thread there are details about the teensy. There is actually a lot of hardware out there today for little money. Thats what makes the SDR DSP approach interesting and for me at least the next thing to take a run at. Regards Paul WB8TSL Hi Paul: I have looked at the Teensy 4.0 for use as a WWVB SDR receiver. The problems I have are: 1.) PJRC (the designer/manufacturer) has gone out of their way to block access to the standard ARM SWD programming interface, and you must go through the unique USB loader executable and programming interface if you want to program the board. It is awkward to use a normal development environment such as NXP's MCUXpresso with a standard programming interface. It is really intended for use with the provided Arduino programming environment. I'm not so sure about that. There's quite a few folks using ARM toolchains and not using the USB loader. For that matter, if you can generate an executable, in any fashion, you can use their loader. I've done it with a 3.2, but not the 4.0, so maybe there's a hiccup.. But usually, the support forum has a wealth of information. Or TyQT, which is what I use a lot with Teensy boards - it will reflash it, reboot, etc. Yeah, you don't get a debugger - you have to toggle pins and use a scope, or printf() googling Teensy 4.0 ARM SWD might turn up useful stuff. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
Graham I appreciate the insights. I am literally just attempting to use teensy for the wwvb AM time decode. The historic timecode is easily done with a $2 chip if you could still get them. I use the arduino IDE and the funny things you have to do with alternate chips like STM arm... Also the restrictions. But this is about experimenting at 60 KHz and sampling. So I expect trouble and failure. Perhaps a switch to something else. But I need to start someplace and this was cheap enough. In theory it arrives today. Regards Paul. WB8TSL On Fri, Oct 16, 2020 at 2:04 PM Graham / KE9H wrote: > On Tue, Oct 13, 2020 at 12:19 PM paul swed wrote: > > > Graham take a look earlier in the thread there are details about the > > teensy. There is actually a lot of hardware out there today for little > > money. Thats what makes the SDR DSP approach interesting and for me at > > least the next thing to take a run at. > > Regards > > Paul > > WB8TSL > > > > > > Hi Paul: > > I have looked at the Teensy 4.0 for use as a WWVB SDR receiver. > > The problems I have are: > > 1.) PJRC (the designer/manufacturer) has gone out of their way to block > access to the standard ARM SWD programming interface, and you must go > through the unique USB loader executable and programming interface if you > want to program the board. It is awkward to use a normal development > environment such as NXP's MCUXpresso with a standard programming interface. > It is really intended for use with the provided Arduino programming > environment. > > 2.) If you use the provided Arduino IDE/environment, then the provided DSP > functions are restricted to the 16 bit versions. I prefer the ARM 32 bit > versions to go with my 19 to 24 bit data converter. > > 3.) I have found that the iMX RT1062 processor will only run at the > advertised 600 MHz speed, if it is exclusively executing from onboard > "tightly coupled RAM". If your program is large enough to require using the > OCRAM, then it slows down to 1/4 speed. If you need even more memory > space, and you try to use the provided external QSPI Flash, then it slows > down to about 1/32 speed. What it effectively does is run at some blend of > those speeds as it fetches cache and variously accesses the different > memories. Memory planning is critical for maximum performance. > > --- Graham > > == > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
On 10/16/20 9:08 AM, Graham / KE9H wrote: On Tue, Oct 13, 2020 at 12:19 PM paul swed wrote: Graham take a look earlier in the thread there are details about the teensy. There is actually a lot of hardware out there today for little money. Thats what makes the SDR DSP approach interesting and for me at least the next thing to take a run at. Regards Paul WB8TSL Hi Paul: I have looked at the Teensy 4.0 for use as a WWVB SDR receiver. The problems I have are: 1.) PJRC (the designer/manufacturer) has gone out of their way to block access to the standard ARM SWD programming interface, and you must go through the unique USB loader executable and programming interface if you want to program the board. It is awkward to use a normal development environment such as NXP's MCUXpresso with a standard programming interface. It is really intended for use with the provided Arduino programming environment. I'm not so sure about that. There's quite a few folks using ARM toolchains and not using the USB loader. For that matter, if you can generate an executable, in any fashion, you can use their loader. I've done it with a 3.2, but not the 4.0, so maybe there's a hiccup.. But usually, the support forum has a wealth of information. 2.) If you use the provided Arduino IDE/environment, then the provided DSP functions are restricted to the 16 bit versions. I prefer the ARM 32 bit versions to go with my 19 to 24 bit data converter. 3.) I have found that the iMX RT1062 processor will only run at the advertised 600 MHz speed, if it is exclusively executing from onboard "tightly coupled RAM". If your program is large enough to require using the OCRAM, then it slows down to 1/4 speed. If you need even more memory space, and you try to use the provided external QSPI Flash, then it slows down to about 1/32 speed. What it effectively does is run at some blend of those speeds as it fetches cache and variously accesses the different memories. Memory planning is critical for maximum performance. Always the case with microcontrollers... I don't know that you'll need that fast, though. I ran 32 point FFTs in real time at 100kHz sample rate on a Teensy 3.2 at 72 MHz (actually, it also ran on a Teensy 3.1 at 48 MHz), as well as a a FIR decimator. For this application, you basically need to implement a Costas loop to demodulate the PSK signal. So that's a few multiplies and adds per input sample for the mixers, a table lookup or CORDIC for the sin/cos, and then the loop filters. The signal is narrow band too.. It might be easier to sample at something like 240 kHz (4x input signal), then do a downconvert to baseband I/Q (using ++--), a decimation with a CIC to a few kHz, then do your Costas loop. One trick used in the GPS world (and also in the "IF sampling" world) is to sample at a rate which puts the aliased input signal at Fs/4. Some of JPL's radios sample a 112.5 MHz IF with a 50 MHz sampling clock, for instance. The GPS people like to pick a sample rate that makes sure that even with maximum Doppler, the Doppler offset is always positive in the aliased passband. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
On Tue, Oct 13, 2020 at 12:19 PM paul swed wrote: > Graham take a look earlier in the thread there are details about the > teensy. There is actually a lot of hardware out there today for little > money. Thats what makes the SDR DSP approach interesting and for me at > least the next thing to take a run at. > Regards > Paul > WB8TSL > > > Hi Paul: I have looked at the Teensy 4.0 for use as a WWVB SDR receiver. The problems I have are: 1.) PJRC (the designer/manufacturer) has gone out of their way to block access to the standard ARM SWD programming interface, and you must go through the unique USB loader executable and programming interface if you want to program the board. It is awkward to use a normal development environment such as NXP's MCUXpresso with a standard programming interface. It is really intended for use with the provided Arduino programming environment. 2.) If you use the provided Arduino IDE/environment, then the provided DSP functions are restricted to the 16 bit versions. I prefer the ARM 32 bit versions to go with my 19 to 24 bit data converter. 3.) I have found that the iMX RT1062 processor will only run at the advertised 600 MHz speed, if it is exclusively executing from onboard "tightly coupled RAM". If your program is large enough to require using the OCRAM, then it slows down to 1/4 speed. If you need even more memory space, and you try to use the provided external QSPI Flash, then it slows down to about 1/32 speed. What it effectively does is run at some blend of those speeds as it fetches cache and variously accesses the different memories. Memory planning is critical for maximum performance. --- Graham == ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
Graham take a look earlier in the thread there are details about the teensy. There is actually a lot of hardware out there today for little money. Thats what makes the SDR DSP approach interesting and for me at least the next thing to take a run at. Regards Paul WB8TSL On Tue, Oct 13, 2020 at 10:31 AM Graham / KE9H wrote: > There are inexpensive CODECs or A-->D converters that are designed for > audio, that can be clocked up to 192 ksps or 200 ksps with 24 bit > resolution. (Typically 18 or 19 effective bits, 3.0 V p-to-p full scale) > They have built in Nyquist filters that scale with the sampling frequency, > so a Nyquist frequency of 100 kHz is very comfortable for receiving a 60 > kHz signal. They use standard I2S audio interface, although other > interfaces are typically options. > > After that it is SMOP, as they say. (Simple Matter Of Programming). :-) > > --- Graham > > == > > > On Fri, Oct 9, 2020 at 12:58 PM paul swed wrote: > > > after the bpsk is removed true. I have done that. A simple RC filter and > a > > 100K over 50ohm divider to get the signal to a reasonable level. Add a > > coupling cap because all of the old receivers output a preamp voltage. > > > > On Fri, Oct 9, 2020 at 11:35 AM Bob kb8tq wrote: > > > > > Hi > > > > > > For a full setup, you could do it a lot of ways. A setup of: > > > > > > Antenna -> front end -> ADC -> MCU -> D/A would be one approach. > Various > > > bits like a local clock also would get into the design. There are > *many* > > > other > > > approaches. > > > > > > == > > > > > > There are a lot of D/A’s that will clock in the 100’s of KHz range. If > > you > > > are only > > > trying to come up with an analog of a WWVB signal the “10 bit” D/A’s > > found > > > in > > > some MCU’s would do the trick. In the setup above, the ADC would likely > > be > > > harder to come up with than the DAC. > > > > > > Since you are only trying to come up with a carrier, the need for a D/A > > is > > > not > > > an absolute one. Taking a square wave of some sort and filtering it a > bit > > > would > > > be adequate to drive most of these old WWVB receivers. > > > > > > Bob > > > > > > > On Oct 8, 2020, at 11:42 PM, Hal Murray > > wrote: > > > > > > > > > > > > I assume it needs an antenna, front end, and D/A. > > > > > > > > What's available in the way of D/A that's good for 60KHz? Is the > > > problem > > > > easier if the D/A box has external clocking? > > > > > > > > -- > > > > These are my opinions. I hate spam. > > > > > > > > > > > > > > > > > > > > ___ > > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > and follow the instructions there. > > > > > > > > > ___ > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
There are inexpensive CODECs or A-->D converters that are designed for audio, that can be clocked up to 192 ksps or 200 ksps with 24 bit resolution. (Typically 18 or 19 effective bits, 3.0 V p-to-p full scale) They have built in Nyquist filters that scale with the sampling frequency, so a Nyquist frequency of 100 kHz is very comfortable for receiving a 60 kHz signal. They use standard I2S audio interface, although other interfaces are typically options. After that it is SMOP, as they say. (Simple Matter Of Programming). :-) --- Graham == On Fri, Oct 9, 2020 at 12:58 PM paul swed wrote: > after the bpsk is removed true. I have done that. A simple RC filter and a > 100K over 50ohm divider to get the signal to a reasonable level. Add a > coupling cap because all of the old receivers output a preamp voltage. > > On Fri, Oct 9, 2020 at 11:35 AM Bob kb8tq wrote: > > > Hi > > > > For a full setup, you could do it a lot of ways. A setup of: > > > > Antenna -> front end -> ADC -> MCU -> D/A would be one approach. Various > > bits like a local clock also would get into the design. There are *many* > > other > > approaches. > > > > == > > > > There are a lot of D/A’s that will clock in the 100’s of KHz range. If > you > > are only > > trying to come up with an analog of a WWVB signal the “10 bit” D/A’s > found > > in > > some MCU’s would do the trick. In the setup above, the ADC would likely > be > > harder to come up with than the DAC. > > > > Since you are only trying to come up with a carrier, the need for a D/A > is > > not > > an absolute one. Taking a square wave of some sort and filtering it a bit > > would > > be adequate to drive most of these old WWVB receivers. > > > > Bob > > > > > On Oct 8, 2020, at 11:42 PM, Hal Murray > wrote: > > > > > > > > > I assume it needs an antenna, front end, and D/A. > > > > > > What's available in the way of D/A that's good for 60KHz? Is the > > problem > > > easier if the D/A box has external clocking? > > > > > > -- > > > These are my opinions. I hate spam. > > > > > > > > > > > > > > > ___ > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
after the bpsk is removed true. I have done that. A simple RC filter and a 100K over 50ohm divider to get the signal to a reasonable level. Add a coupling cap because all of the old receivers output a preamp voltage. On Fri, Oct 9, 2020 at 11:35 AM Bob kb8tq wrote: > Hi > > For a full setup, you could do it a lot of ways. A setup of: > > Antenna -> front end -> ADC -> MCU -> D/A would be one approach. Various > bits like a local clock also would get into the design. There are *many* > other > approaches. > > == > > There are a lot of D/A’s that will clock in the 100’s of KHz range. If you > are only > trying to come up with an analog of a WWVB signal the “10 bit” D/A’s found > in > some MCU’s would do the trick. In the setup above, the ADC would likely be > harder to come up with than the DAC. > > Since you are only trying to come up with a carrier, the need for a D/A is > not > an absolute one. Taking a square wave of some sort and filtering it a bit > would > be adequate to drive most of these old WWVB receivers. > > Bob > > > On Oct 8, 2020, at 11:42 PM, Hal Murray wrote: > > > > > > I assume it needs an antenna, front end, and D/A. > > > > What's available in the way of D/A that's good for 60KHz? Is the > problem > > easier if the D/A box has external clocking? > > > > -- > > These are my opinions. I hate spam. > > > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
Hi For a full setup, you could do it a lot of ways. A setup of: Antenna -> front end -> ADC -> MCU -> D/A would be one approach. Various bits like a local clock also would get into the design. There are *many* other approaches. == There are a lot of D/A’s that will clock in the 100’s of KHz range. If you are only trying to come up with an analog of a WWVB signal the “10 bit” D/A’s found in some MCU’s would do the trick. In the setup above, the ADC would likely be harder to come up with than the DAC. Since you are only trying to come up with a carrier, the need for a D/A is not an absolute one. Taking a square wave of some sort and filtering it a bit would be adequate to drive most of these old WWVB receivers. Bob > On Oct 8, 2020, at 11:42 PM, Hal Murray wrote: > > > I assume it needs an antenna, front end, and D/A. > > What's available in the way of D/A that's good for 60KHz? Is the problem > easier if the D/A box has external clocking? > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] What's available in the way of DSP for new WWVB?
Hi Hal I think your asking for an A/D if this is a receiver. I can speak to the front end. In the the US the signal in the east is some 10-60 uv during the day. To leverage the full scale of the A/D that has to be amplified to the A/Ds full scale. Say 1-2 V. Thats easily some 90DBv of gain. So a good front end TRF design with filtering would work great. The next part of your question is a lot harder. What use will the receiver be used for? Everything I see is that the signal is sampled as I & Q The carrier and -90 degrees. The carrier ends up being locked at a higher frequency perhaps 10X 60 KHz and that is used with two A/Ds. For me it gets muddy just about here. Could 1 A/D be used and the sampling done in the data domain? Suspect thats a yes. Then when you have the samples what to do with them. That goes back to the what does the receiver do question. Regards Paul On Fri, Oct 9, 2020 at 12:20 AM Hal Murray wrote: > > I assume it needs an antenna, front end, and D/A. > > What's available in the way of D/A that's good for 60KHz? Is the problem > easier if the D/A box has external clocking? > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] What's available in the way of DSP for new WWVB?
I assume it needs an antenna, front end, and D/A. What's available in the way of D/A that's good for 60KHz? Is the problem easier if the D/A box has external clocking? -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
