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WLAN card to generate pulsed RF?

Started by Joerg October 26, 2006
Joerg wrote:
> Hello Nico, > >>> >>>>> AFAIR I got over 50bps out of it but the flyback transformer in the >>>>> monitor was screaming so bad that I stopped. Don't know what an >>>>> LCD could do though. >>>> >>>> >>>> >>>> Probably less. You can forget blinking the cold cathode lamp - the >>>> invertor is probably too slow to drive in all cases. I guess assuming >> >> >> >> The inverter can be driven on/off at several 10s of Hz, but it takes >> several 10s of ms for the driver to reach full output. >> > > Yes, but I'd rather not flick the inverter unless I know exactly how it > is designed. PWM circuits often exhibit some bizarre pathologies and > some lamps might not like this mode either.
"bizarre pathologies" - thats a lovely turn of phrase Joerg! They also tend to occur more during power-up and power-down, so thats proobably asking for trouble.
> >> >>>> a 30 Hz refresh rate will be conservative enough, and with some more >>>> conservativism you go down to the 10 bpS, which I am sure can >>>> be doubled if you tweak all of the above and some more :-), but >>>> that will be about all, I guess. >>>> >>> >>> There is no easy access to the CCFL generator. But many LCD can >>> probably be cycled at 30 Hz because that is the frame repetition rate >>> of US television. >> >> >> >> That depends entirely on the speed of the LCD screen. Latency of TFT >> lies somewhere between 4 to 10ms. The latency number specified for TFT >> screens is the sum of the time required to go from black to white and >> from white to black. A screen rated for 8ms may have a white->black >> time of 2ms and a black->white time of 6ms. >> >> With OpenGL it is possible to update the screen buffer on vertical >> blanks. Since almost every TFT screen is driven at 50Hz, you could >> make the display flash completely at a rate of 25Hz (40ms period). A >> good Windows programmer should be able to program something like this >> in a few days. >> > > Thanks, Nico. That is excellent information. It wouldn't be necessary to > swing between the extremes, a good photo receiver circuit could work > with 25% modulation or even less. >
Can you make a crude accelerometer out of a piezo speaker, and do the audio sans hole? Cheers Terry
Joerg wrote:
> Hello Robert, > > > [ ... ] > > > > >>>What is that you have that continues to require the DOS box that can't > >>>be replaced with Win32 command line code? > >> > >>Any program that is supplied as binary (.com or .exe), since the > >>original company might not exist anymore. > > > > Certainly that's the usual case (or something homegrown and not moved > > to 32 bit). That's usually the case for one or two point > > installations, but the poster I was responding to claimed this made > > Win64 unusable for their entire office and lab. > > > > So the question remains, why can't they move to a Win32 app? In many > > cases the reason is either inertia (haven't upgrade my copy of > > SuperWhatsit since 1994) or misconception (Command Prompt = DOS Box), > > in which case it's not a real limitation. > > > > There are some SuperWhatsits that simply cannot be upgraded. Mostly this > happens when a university group that produced excellent work and useful > routines has disbanded. Either because they moved on to something new or > because the professor retired. Academia isn't exactly known to maintain > older things like we do in industry. > > Example: "FilterDesign" from Prof.Mildenberger, Wiesbaden, Germany. He > retired and now they even took down his web page. It's a great and > rather indispensable program when you have to design wave digital > filters. The PC switches to full screen DOS to use it. Besides routines > from TI there isn't much else. Those routines are also hardcore DOS, > including one that was released this September. > > Bottomline is that if MS drops DOS this business will not upgrade > anymore for a long time and then possibly migrate to another OS. Why > should we upgrade if that reduces productivity?
OK, but how many people in a given shop are likely to use it? And for the next few years is running a second PC, 32 bit Windows (there will be a 32 bit version of Vista), or one of the VMs a really unacceptable solution? I certainly sympathize, I have some DOS and Win16 stuff I have to support too. But, this is not unlike the complaint about the lack of legacy ports on new PCs and laptops. The fraction of users this will impact is very, very small. And in both cases, there are workarounds available.
"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message 
news:Eya1h.2229$s6.2097@newssvr11.news.prodigy.com...
> Hello Alex, >
> > >> What about wireless usb ? >> Probably currently to expensive and nothing available (easily) >> but will get cheaper and more available. >> Supposedly in some of the current pc chipsets but not enabled. >> > > Anything that sticks out from a laptop will eventually break in the field. > Unsually in the least convenient place (several miles up a dirt road in > pouring rain...). Or the USB stick fell out of the tool box but who knows > where.
No not an adaptor for wireless but wireless usb (uwb) supposed to be already in some of Intels new chipsets. Supports up to 480Mbps up to a few metres away. Alex
Hello Terry,

>>> >>>> Well, that's exactly the point. I'd have to uncouple the WLAN card from >>>> it's habit of halting whenever something else talks. At least for a few >>>> seconds. However, that might sometimes not be permitted by the >>>> authorities. A way around that would be burst transmissions as long as >>>> it is legal. Net data rates as low as 2400bps would be quite >>>> acceptable. >>>> Even less if needed since the user could place the device on the table >>>> and then go do something else >>> >>> Yes, and the danger of interfering with regulation or the protocol is >>> one of the reasons WLAN vendors are not going to let you touch the >>> firmware. >>> >> That's what I am afraid might stop this approach dead in the tracks. >> Unless it could at least be (legally) brought into a burst more where >> each burst is interpreted as a bit. >> >>> >>>> The only other option I could think of (and I have done that before) is >>>> to provide a photodiode and let the LCD screen flash. However, that is >>>> really slow and can annoy others who have to work close to that laptop. >>> >>> >>> >>> >>> If you get the photodiode close enough, you only need to flash a small >>> area, or maybe you can alternate between colors that appear to have >>> similar brightness for human perception, but still offer enough >>> contrast for the photodiode. >>> >> >> That would require filtering but could be done. At least it's better >> than using audio because that would be really annoying to others. >> > > Hi Joerg, > > why not take a leaf out of teenagers book of phone tricks, and use 20kHz > audio... >
Ask our shepherd-mix for her opinion about 20kHz ;-) Whenever I do high-frequency audio stuff or PWM in the lab and a ferrite core gets a bit loose she dashes off to the other end of the building. The rottie-mix keeps snoring away under a table. -- Regards, Joerg http://www.analogconsultants.com
Hello Terry,

> Joerg wrote: > >> Hello Nico, >> >>>> >>>>>> AFAIR I got over 50bps out of it but the flyback transformer in the >>>>>> monitor was screaming so bad that I stopped. Don't know what an >>>>>> LCD could do though. >>>>> >>>>> >>>>> >>>>> >>>>> Probably less. You can forget blinking the cold cathode lamp - the >>>>> invertor is probably too slow to drive in all cases. I guess assuming >>> >>> >>> >>> >>> The inverter can be driven on/off at several 10s of Hz, but it takes >>> several 10s of ms for the driver to reach full output. >>> >> >> Yes, but I'd rather not flick the inverter unless I know exactly how >> it is designed. PWM circuits often exhibit some bizarre pathologies >> and some lamps might not like this mode either. > > > "bizarre pathologies" - thats a lovely turn of phrase Joerg! They also > tend to occur more during power-up and power-down, so thats proobably > asking for trouble. > >> >>> >>>>> a 30 Hz refresh rate will be conservative enough, and with some more >>>>> conservativism you go down to the 10 bpS, which I am sure can >>>>> be doubled if you tweak all of the above and some more :-), but >>>>> that will be about all, I guess. >>>>> >>>> >>>> There is no easy access to the CCFL generator. But many LCD can >>>> probably be cycled at 30 Hz because that is the frame repetition >>>> rate of US television. >>> >>> >>> >>> >>> That depends entirely on the speed of the LCD screen. Latency of TFT >>> lies somewhere between 4 to 10ms. The latency number specified for TFT >>> screens is the sum of the time required to go from black to white and >>> from white to black. A screen rated for 8ms may have a white->black >>> time of 2ms and a black->white time of 6ms. >>> >>> With OpenGL it is possible to update the screen buffer on vertical >>> blanks. Since almost every TFT screen is driven at 50Hz, you could >>> make the display flash completely at a rate of 25Hz (40ms period). A >>> good Windows programmer should be able to program something like this >>> in a few days. >>> >> >> Thanks, Nico. That is excellent information. It wouldn't be necessary >> to swing between the extremes, a good photo receiver circuit could >> work with 25% modulation or even less. >> > > Can you make a crude accelerometer out of a piezo speaker, and do the > audio sans hole?
Yes. However, when winds and other noises come up the SNR quickly goes to pots. -- Regards, Joerg http://www.analogconsultants.com
Hello Robert,

> Joerg wrote: > >>Hello Robert, >> >> >>[ ... ] >> >> >>>>>What is that you have that continues to require the DOS box that can't >>>>>be replaced with Win32 command line code? >>>> >>>>Any program that is supplied as binary (.com or .exe), since the >>>>original company might not exist anymore. >>> >>>Certainly that's the usual case (or something homegrown and not moved >>>to 32 bit). That's usually the case for one or two point >>>installations, but the poster I was responding to claimed this made >>>Win64 unusable for their entire office and lab. >>> >>>So the question remains, why can't they move to a Win32 app? In many >>>cases the reason is either inertia (haven't upgrade my copy of >>>SuperWhatsit since 1994) or misconception (Command Prompt = DOS Box), >>>in which case it's not a real limitation. >>> >> >>There are some SuperWhatsits that simply cannot be upgraded. Mostly this >>happens when a university group that produced excellent work and useful >>routines has disbanded. Either because they moved on to something new or >>because the professor retired. Academia isn't exactly known to maintain >>older things like we do in industry. >> >>Example: "FilterDesign" from Prof.Mildenberger, Wiesbaden, Germany. He >>retired and now they even took down his web page. It's a great and >>rather indispensable program when you have to design wave digital >>filters. The PC switches to full screen DOS to use it. Besides routines >>from TI there isn't much else. Those routines are also hardcore DOS, >>including one that was released this September. >> >>Bottomline is that if MS drops DOS this business will not upgrade >>anymore for a long time and then possibly migrate to another OS. Why >>should we upgrade if that reduces productivity? > > > > OK, but how many people in a given shop are likely to use it? And for > the next few years is running a second PC, 32 bit Windows (there will > be a 32 bit version of Vista), or one of the VMs a really unacceptable > solution? >
If a VM is able to run legacy DOS, fine. Otherwise no, since I am not inclined to schlepp around two laptops ;-)
> I certainly sympathize, I have some DOS and Win16 stuff I have to > support too. > > But, this is not unlike the complaint about the lack of legacy ports on > new PCs and laptops. The fraction of users this will impact is very, > very small. And in both cases, there are workarounds available. >
Nearly all (in my case all) programmer pods and the like have become available as USB versions. But in the world of specialized design software that isn't happening for works that originated at universities and other research facilities. For much of that there is nobody around anymore that would be able to change it. Often there isn't even anyone who would know where the source code files are. -- Regards, Joerg http://www.analogconsultants.com
Hello Alex,

>> >>>What about wireless usb ? >>>Probably currently to expensive and nothing available (easily) >>>but will get cheaper and more available. >>>Supposedly in some of the current pc chipsets but not enabled. >>> >> >>Anything that sticks out from a laptop will eventually break in the field. >>Unsually in the least convenient place (several miles up a dirt road in >>pouring rain...). Or the USB stick fell out of the tool box but who knows >>where. > > > No not an adaptor for wireless but wireless usb (uwb) > supposed to be already in some of Intels new chipsets. > Supports up to 480Mbps up to a few metres away. >
But I am afraid it will be some time until laptops have that built in. Also, most agencies or businesses won't allow their staff to order new ones as long as the "old" ones haven't reached the end of the depreciation tables. Something like three years, usually. Also, I'd need more than a few meters. More like 30 or so, and it has to go from inside a vehicle to a pole. In rain, sleet, hail, loads of thawed and re-frozen snow, the works. -- Regards, Joerg http://www.analogconsultants.com
Hi Joerg,

Joerg wrote:
> Hello Terry, > >>>> >>>>> Well, that's exactly the point. I'd have to uncouple the WLAN card >>>>> from >>>>> it's habit of halting whenever something else talks. At least for a >>>>> few >>>>> seconds. However, that might sometimes not be permitted by the >>>>> authorities. A way around that would be burst transmissions as long as >>>>> it is legal. Net data rates as low as 2400bps would be quite >>>>> acceptable. >>>>> Even less if needed since the user could place the device on the table >>>>> and then go do something else >>>> >>>> >>>> Yes, and the danger of interfering with regulation or the protocol is >>>> one of the reasons WLAN vendors are not going to let you touch the >>>> firmware. >>>> >>> That's what I am afraid might stop this approach dead in the tracks. >>> Unless it could at least be (legally) brought into a burst more where >>> each burst is interpreted as a bit. >>> >>>> >>>>> The only other option I could think of (and I have done that >>>>> before) is >>>>> to provide a photodiode and let the LCD screen flash. However, that is >>>>> really slow and can annoy others who have to work close to that >>>>> laptop. >>>> >>>> >>>> >>>> >>>> >>>> If you get the photodiode close enough, you only need to flash a small >>>> area, or maybe you can alternate between colors that appear to have >>>> similar brightness for human perception, but still offer enough >>>> contrast for the photodiode. >>>> >>> >>> That would require filtering but could be done. At least it's better >>> than using audio because that would be really annoying to others. >>> >> >> Hi Joerg, >> >> why not take a leaf out of teenagers book of phone tricks, and use >> 20kHz audio... >> > > Ask our shepherd-mix for her opinion about 20kHz ;-) > > Whenever I do high-frequency audio stuff or PWM in the lab and a ferrite > core gets a bit loose she dashes off to the other end of the building. > The rottie-mix keeps snoring away under a table. >
LOL :) can you use a bidirectional solenoid as the transmitter, and do the "audio" at 5Hz? Cheers Terry
Hello Terry,


>>> why not take a leaf out of teenagers book of phone tricks, and use >>> 20kHz audio... >>> >> >> Ask our shepherd-mix for her opinion about 20kHz ;-) >> >> Whenever I do high-frequency audio stuff or PWM in the lab and a >> ferrite core gets a bit loose she dashes off to the other end of the >> building. The rottie-mix keeps snoring away under a table. >> > > LOL :) > > can you use a bidirectional solenoid as the transmitter, and do the > "audio" at 5Hz? >
Probably. But that would require some patience on the part of the folks that have to do the firmware updates in the field. And who knows, maybe that would bother the whales in the oceans :-) -- Regards, Joerg http://www.analogconsultants.com
> > can you use a bidirectional solenoid as the transmitter, and do the > "audio" at 5Hz? > > Cheers > Terry
Sounds like NFC. That will give you at least 100 kb/s Wim