JosephKK wrote:> Joerg notthisjoergsch@removethispacbell.net posted to > sci.electronics.design: > >> Paul Keinanen wrote: >>> On Wed, 24 Oct 2007 13:34:29 -0700, Joerg >>> <notthisjoergsch@removethispacbell.net> wrote: >>> >>>> Hello Folks, >>>> >>>> After some Google searching and perusing the sites of the usual >>>> contenders I only found one uC family that has serious on-chip RF >>>> transceiver capabilities, the Cypress CYWUSB6953 and its brethren. >>>> rfPICs and others usually only have a transmitter. >>>> >>>> Anyhow, the Cypress will only serve 2.45GHz but I need the lower >>>> UHF bands for range reasons. Is anything coming down the pike soon >>>> or will that have to remain a two-chip solution? >>> It would help if you had specified the country in which it should >>> operate. The frequency bands, the power levels and duty cycles vary >>> with country or at least with continent. >>> >> As many countries as possible. Definitely US, Canada, Europe and in >> and around the Gulf of Mexico, other cases also Asia. That leaves >> 433MHz and 2.45GHz. Or frequencies below 100MHz but there aren't any >> integrated solutions for those. >> >> >>> You said that the range was too short on 2.45 GHz. What kind of >>> propagation environment do you have ? Free space, lot of thick >>> trees, indoor or what ? >>> >> All of the above, usually comms between a pod inside the house to >> equipment outside. I guess our house would be the worst case, >> woodframe construction with aluminum backed insulation inside the >> walls. >> >> >>> In a free space environment, the capture area of an omnidirectional >>> receiver antenna at a higher frequency can get quite small, thus >>> the receiver signal will be weaker. Also a lot of wet trees will >>> attenuate the 2.45 GHz signal. >>> >>> On the other hand, in typical indoor situations and at the streets >>> of a large city, there are going to be plenty of reflections and >>> the propagation is more or less independent of the frequency. The >>> shorter wavelength might even propagate more easily through narrow >>> slits in air conditioning ducts etc. >>> >> All I can say that around our house 2.45GHz does not work reliably >> at all. <200MHz works excellent. >> > > Now you are talking VHF instead of UHF. >Yes, my dream would always be VHF for this stuff. Unfortunately no chips and the countries on this planet haven't come to agreements there. -- Regards, Joerg http://www.analogconsultants.com/
Micro controllers with UHF transceivers?
Started by ●October 24, 2007
Reply by ●October 27, 20072007-10-27
Reply by ●October 27, 20072007-10-27
In article <slrnfi44bi.98o.andrews@sdf.lonestar.org>, Andrew Smallshaw <andrews@sdf.lonestar.org> writes:> > Be careful about those bands: I don't know about other areas but > here in the UK the 35MHz and 40MHz are set aside specifically for > radio control aircraft and surface vehicles respectively. Given > the safety implications of interference on 35MHz in particular I > don't think Ofcom would react too kindly if they heard about illegal > transmissions on those frequencies. >I should also point out that within the UK the license free bands are licensed (with a few exceptions) for transmissions from ground based units only. The details are in OFCOM document IR 2030, last updated about a year ago. BTW, I haven't seen any discussion of the 458MHz license free band. Is that a Europe only band ? Simon. -- Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP Microsoft: Bringing you 1980's technology to a 21st century world
Reply by ●October 28, 20072007-10-28
On Wed, 24 Oct 2007 13:34:29 -0700, Joerg <notthisjoergsch@removethispacbell.net> wrote:>Hello Folks, > >After some Google searching and perusing the sites of the usual >contenders I only found one uC family that has serious on-chip RF >transceiver capabilities, the Cypress CYWUSB6953 and its brethren. >rfPICs and others usually only have a transmitter. > >Anyhow, the Cypress will only serve 2.45GHz but I need the lower UHF >bands for range reasons. Is anything coming down the pike soon or will >that have to remain a two-chip solution?I think that there is a problem in your approach. You try to do a one/two chip selection before fully understanding the communication requirements. At least this would rule out some frequency bands. As far as I understand, the only specification for the system is about 100 m range and usability in as many countries as possible. I think that you should determine at least the following parameters for the communication system: * data rate needed, both up- and downlink (and hence bandwidth and regulatory limits) * available DC power both uplink and downlink * available (antenna) size at up/downlink, for instance a big fixed base station TX antenna at 13.56 MHz might be OK, but the efficiency of a small portable system would be very bad After these decisions, it might be possible to select among the available bands a suitable one/two chip system. Paul
Reply by ●October 28, 20072007-10-28
Paul Keinanen wrote:> On Wed, 24 Oct 2007 13:34:29 -0700, Joerg > <notthisjoergsch@removethispacbell.net> wrote: > >> Hello Folks, >> >> After some Google searching and perusing the sites of the usual >> contenders I only found one uC family that has serious on-chip RF >> transceiver capabilities, the Cypress CYWUSB6953 and its brethren. >> rfPICs and others usually only have a transmitter. >> >> Anyhow, the Cypress will only serve 2.45GHz but I need the lower UHF >> bands for range reasons. Is anything coming down the pike soon or will >> that have to remain a two-chip solution? > > I think that there is a problem in your approach. > > You try to do a one/two chip selection before fully understanding the > communication requirements. At least this would rule out some > frequency bands. > > As far as I understand, the only specification for the system is about > 100 m range and usability in as many countries as possible. >It's all pretty flexible in most cases.> I think that you should determine at least the following parameters > for the communication system: > > * data rate needed, both up- and downlink (and hence bandwidth and > regulatory limits)Very low, basically no more than a TV remote has to communicate. 300bps would be plenty.> * available DC power both uplink and downlinkNot a concern, except for the occasional handheld remote. But even there it ain't too important because it can turn itself on/off with bottun presses.> * available (antenna) size at up/downlink, for instance a big fixed > base station TX antenna at 13.56 MHz might be OK, but the efficiency > of a small portable system would be very bad >You can get plenty enough range on anything below 100MHz with very short antennas. Done it many times. But the "international" 13.56MHz and 27.12MHz bands are polluted by a lot of fairly rogue transmitters, with some of which I wonder how they ever passed certification.> After these decisions, it might be possible to select among the > available bands a suitable one/two chip system. >-- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 28, 20072007-10-28
On Oct 27, 5:47 pm, JosephKK <joseph_barr...@sbcglobal.net> wrote:> That was some odd pasting.Huh?
Reply by ●October 28, 20072007-10-28
On Oct 27, 12:52 pm, Joerg <notthisjoerg...@removethispacbell.net> wrote:> Thanks. But same as usual, only TX with uC, not transceivers with uC.If it's any consolation, I think the market will be saturated with these devices in 18 months. There is some new European boondoggle going on (at least this one will make money, unlike RoHS). I didn't pay much attention but it is something to do with energy efficiency/ heating.
Reply by ●October 28, 20072007-10-28
larwe wrote:> On Oct 27, 12:52 pm, Joerg <notthisjoerg...@removethispacbell.net> > wrote: > >> Thanks. But same as usual, only TX with uC, not transceivers with uC. > > If it's any consolation, I think the market will be saturated with > these devices in 18 months. There is some new European boondoggle > going on (at least this one will make money, unlike RoHS). I didn't > pay much attention but it is something to do with energy efficiency/ > heating. >I wouldn't count too much on such political efforts. We had that here in CA at times, the governor even visited Echelon. But the stuff is so expensive that most everyone stays with the true and tried. Or even goes backwards to older technology to wiggle out of the fossil fuel rat race. Like us when we installed wood stoves. My faith in electronic controls of heating equipment has sagged after every repair. My favorite gear is the living room wood stove. Except for the blower speed control (which can be disabled) the number of electronics parts is zilch. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 29, 20072007-10-29
On Sun, 28 Oct 2007 15:24:31 GMT, Joerg <notthisjoergsch@removethispacbell.net> wrote:>Paul Keinanen wrote: >> On Wed, 24 Oct 2007 13:34:29 -0700, Joerg >> <notthisjoergsch@removethispacbell.net> wrote:>> * data rate needed, both up- and downlink (and hence bandwidth and >> regulatory limits) > > >Very low, basically no more than a TV remote has to communicate. 300bps >would be plenty.That significantly increases the range. However, the frequency accuracy and temperature stability requirements can become quite demanding and it would be questionable, if a built in crystal oscillator would be stable enough.>> * available (antenna) size at up/downlink, for instance a big fixed >> base station TX antenna at 13.56 MHz might be OK, but the efficiency >> of a small portable system would be very bad >> > >You can get plenty enough range on anything below 100MHz with very short >antennas. Done it many times. But the "international" 13.56MHz and >27.12MHz bands are polluted by a lot of fairly rogue transmitters, with >some of which I wonder how they ever passed certification.Those frequency bands as well as 2.45 GHz are known as ISM (Industrial, Scientific, Medical) bands and they were _not_ intended for radio communication but for e.g. RF-heating of the human body, food and plastics (welding). Later on, various license free radio communication applications were allowed on this "wasteland" of spectrum and the communication systems had to cope with the ISM usage e.g. by using spread spectrum to avoid the interference from ISM devices. If you need some degree of protection for your communication system, you should use a licensed frequency band. Paul
Reply by ●October 29, 20072007-10-29
Paul Keinanen wrote:> On Sun, 28 Oct 2007 15:24:31 GMT, Joerg > <notthisjoergsch@removethispacbell.net> wrote: > >> Paul Keinanen wrote: >>> On Wed, 24 Oct 2007 13:34:29 -0700, Joerg >>> <notthisjoergsch@removethispacbell.net> wrote: > >>> * data rate needed, both up- and downlink (and hence bandwidth and >>> regulatory limits) >> >> Very low, basically no more than a TV remote has to communicate. 300bps >> would be plenty. > > That significantly increases the range. However, the frequency > accuracy and temperature stability requirements can become quite > demanding and it would be questionable, if a built in crystal > oscillator would be stable enough. >On higher frequencies all you can really do is sweep and then AFC-lock. Else it becomes prohibitively expensive.> >>> * available (antenna) size at up/downlink, for instance a big fixed >>> base station TX antenna at 13.56 MHz might be OK, but the efficiency >>> of a small portable system would be very bad >>> >> You can get plenty enough range on anything below 100MHz with very short >> antennas. Done it many times. But the "international" 13.56MHz and >> 27.12MHz bands are polluted by a lot of fairly rogue transmitters, with >> some of which I wonder how they ever passed certification. > > Those frequency bands as well as 2.45 GHz are known as ISM > (Industrial, Scientific, Medical) bands and they were _not_ intended > for radio communication but for e.g. RF-heating of the human body, > food and plastics (welding). > > Later on, various license free radio communication applications were > allowed on this "wasteland" of spectrum and the communication systems > had to cope with the ISM usage e.g. by using spread spectrum to avoid > the interference from ISM devices. > > If you need some degree of protection for your communication system, > you should use a licensed frequency band. >That is very much impossible for consumer gear. I remember when we got our first microwave, pretty much the first people in town, and the radio authority folks in Germany had to come out and bless the "installation". That was a substantial roadblock and later removed. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●October 29, 20072007-10-29
On Mon, 29 Oct 2007 09:04:19 -0700, Joerg <notthisjoergsch@removethispacbell.net> wrote:>Paul Keinanen wrote: >> On Sun, 28 Oct 2007 15:24:31 GMT, Joerg >> <notthisjoergsch@removethispacbell.net> wrote: >> >>> Paul Keinanen wrote: >>>> On Wed, 24 Oct 2007 13:34:29 -0700, Joerg >>>> <notthisjoergsch@removethispacbell.net> wrote: >> >>>> * data rate needed, both up- and downlink (and hence bandwidth and >>>> regulatory limits) >>> >>> Very low, basically no more than a TV remote has to communicate. 300bps >>> would be plenty. >> >> That significantly increases the range. However, the frequency >> accuracy and temperature stability requirements can become quite >> demanding and it would be questionable, if a built in crystal >> oscillator would be stable enough. >> > >On higher frequencies all you can really do is sweep and then AFC-lock. >Else it becomes prohibitively expensive.This is a good system for full-duplex links in areas with low interference. For instance various "Gunnplexer" systems consisting of one more or less stable Gunn diode master station at 10 GHz sends out a constant carrier and the slave station uses frequency locking to lock into that signal and then generates the uplink 100 or 144 MHz above or below the downlink. However, with half duplex communication, you would have to send a very long preamble before the message to allow locking to the incomming signal. If the data rate is below 300 bits/s, which would require about 300 Hz bandwidth with BPSK, you would need less than 1 ppm accuracy at 433 MHz, which would be quite expensive. With 10 ppm accuracy, you definitively would need to scan the 4.3 kHz bandwidth for the signal. This is OK, as long as the desired signal is the only signal within that bandwidth. If many similar signals are within that band, you would have to check for correct code, before proceeding into next carrier. As long as the actual message is quite long, you could tolerate a long synchronisation preamble.>> Those frequency bands as well as 2.45 GHz are known as ISM >> (Industrial, Scientific, Medical) bands and they were _not_ intended >> for radio communication but for e.g. RF-heating of the human body, >> food and plastics (welding). >> >> Later on, various license free radio communication applications were >> allowed on this "wasteland" of spectrum and the communication systems >> had to cope with the ISM usage e.g. by using spread spectrum to avoid >> the interference from ISM devices. >> >> If you need some degree of protection for your communication system, >> you should use a licensed frequency band. >> > >That is very much impossible for consumer gear. I remember when we got >our first microwave, pretty much the first people in town, and the radio >authority folks in Germany had to come out and bless the "installation". >That was a substantial roadblock and later removed.Was that on the former 1.27 GHz ISM band or at 2.45 GHz ? Paul
