Digital wireless systems
john
I programmed Spartan chip to produce serial data ( main_Clock, Data
Clock, Data and Tag ) stream for a DAC. I need to make this system
work with out wires. The main clock is 3MHz, Data clock is 1.5MHz. Can
anybody advice me how to make it digital wireless ( Transmitter plus
receiver). I have not done anything like this before. The DAC will be
at 6 feet away from the Spartan chip.
Thanks
John
linnix
The best way is to modulate your signal at 5.8GHz and embed the phase
correction data into the data stream. I assume the data flow is one-
way only.
john
Yes, The data is flowing in one way. Would you please suggest some
hardware. I am also thinking about bluetooth. Please advice!
Regards,
John
linnix
Bluetooth will not give you 1.5MHz data rate. In fact, 5.8GHz might
not be enough, but the next ISM band is 25GHz.
john
Regards,
John
linnix
The Atmel ATR2820 RF Transceiver would be a good start, but I can't
design your apps without knowing the full spec.
Rich Webb
One-off project or a few dozen or a few hundred thousand? Per week?
A hobby/learning/grow-your-brain project or for sale (and use) by a
third party?
Will UL/CSA/EC/FCC/etc. certification be required?
Are the consequences of a communications failure: none, benign, pretty
bad, or someone dies?
Is this for a medical application (noting that your IP block is from
Wayne State University Medical Center)?
With that out of the way, if you can grind down the data rate a bit
(no pun intended), you're close to being able to use an off-the-shelf
solution like an XBee module, advertised to top out at 1 Mbps.
<http://www.sparkfun.com/commerce/product_info.php?products_id=8695>
--
Rich Webb Norfolk, VA
linnix
> On Mon, 12 May 2008 08:31:59 -0700 (PDT), john
>
> >Hi,
>
> >I programmed Spartan chip to produce serial data ( main_Clock, Data
> >Clock, Data and Tag ) stream for a DAC. I need to make this system
> >work with out wires. The main clock is 3MHz, Data clock is 1.5MHz. Can
> >anybody advice me how to make it digital wireless ( Transmitter plus
> >receiver). I have not done anything like this before. The DAC will be
> >at 6 feet away from the Spartan chip.
>
> One-off project or a few dozen or a few hundred thousand? Per week?
>
> A hobby/learning/grow-your-brain project or for sale (and use) by a
> third party?
>
> Will UL/CSA/EC/FCC/etc. certification be required?
>
> Are the consequences of a communications failure: none, benign, pretty
> bad, or someone dies?
>
> Is this for a medical application (noting that your IP block is from
> Wayne State University Medical Center)?
>
> With that out of the way, if you can grind down the data rate a bit
> (no pun intended), you're close to being able to use an off-the-shelf
> solution like an XBee module, advertised to top out at 1 Mbps.
Take a look at the RF data rate of 250Kbps. Does it mean the same for
me as for you?
john
What do you think about Texas Instrument's IEEE 802.16 (WiMax) chip
set ( TRF1X/2X RF Chipset ).
Please advice!
Regards,
John
linnix
> Hi,
>
> What do you think about Texas Instrument's IEEE 802.16 (WiMax) chip
No.
> set ( TRF1X/2X RF Chipset ).
Maybe.
> Please advice!
Forget about Bluetooth, WiFi, XYZBee, WiAnything. If you want
slicings or channelings, you need 25GHz. To get 1.5MHz data rate, you
need the full bandwidth for 5.8GHz.
john
Why do I need the bandwidth of 5.8GHz. Please advice!
John
linnix
> Why do I need the bandwidth of 5.8GHz. Please advice!
> John
Radio Freguency Modulations and Demodulations.
Joel Koltner
news:77322775-096c-4b35...@l28g2000prd.googlegroups.com...
> Forget about Bluetooth, WiFi, XYZBee, WiAnything. If you want
> slicings or channelings, you need 25GHz. To get 1.5MHz data rate, you
> need the full bandwidth for 5.8GHz.
How many bits at the 1.5MHz rate? In other words, how many Mbps?
Regular old 802.11g wireless routers will get you >50Mbps; channel bonding
(40MHz occupied bandwidth) gets you up to >80Mbps in the best cases... which
is just as good as anything you get on 5.8GHz WiFi. (These are all *average*
throughputs, taken from the "wireless charts" at www.smallnetbuilder.com...)
john
wrote:
Hi,
48 bits at 1.5Mhz rate?
John
linnix
Never mind, Bluetooth 2.0 would be fine. I thought you mean 1.5Mbps
sustained.
Steve
"john" <conph...@hotmail.com> wrote in message
news:04838ece-d2e1-4260...@z72g2000hsb.googlegroups.com...
>
>
> Why do I need the bandwidth of 5.8GHz. Please advice!
> John
You don't need 5.8 GHz of bandwidth, and no one has said that you do. But
because you asked to be able to transmit continuously at 1.5 Mbps, you are
going to need a high carrier frequency. Your responses to various replies
indicate you really don't understand what you are asking for. So if this is
anything but a hobby project, I'd "advice" you to hand this task to someone
with RF experience. What you are trying to do is non-trivial because you
want the equivalent of an unswitched "coax cable in the sky". Most chipsets
that are available assume a much different environment, where data is
packetized, pipeline delays are acceptable, retransmissions on errors or
lost packets are allowed, channel equalization is dynamic, data travels in
two directions (at least for acknowledgements) etc. Accounting for the
overhead of these other things so you can use some vendor's OTS chip set
will only increase your total bandwidth requirements. I think you'll need a
custom solution or else you'll have to scale back your requirements.
Steve
Joel Koltner
> (40MHz occupied bandwidth) gets you up to >80Mbps in the best cases... which
> is just as good as anything you get on 5.8GHz WiFi. (These are all *average*
> throughputs, taken from the "wireless charts" atwww.smallnetbuilder.com...)
That's 72Mbps, so you can just manage it with the best WiFi routers out there.
Go visit smallnetbuilder.com for the particular models...
linnix
wrote:
> "john" <conphil...@hotmail.com> wrote in message
>
> news:ef81eccf-84e9-497f...@j22g2000hsf.googlegroups.com...
> On May 12, 4:21 pm, "Joel Koltner" <zapwireDASHgro...@yahoo.com>
> wrote:> Regular old 802.11g wireless routers will get you >50Mbps; channel bonding
> > (40MHz occupied bandwidth) gets you up to >80Mbps in the best cases... which
> > is just as good as anything you get on 5.8GHz WiFi. (These are all *average*
> > throughputs, taken from the "wireless charts" atwww.smallnetbuilder.com...)
>
> "48 bits at 1.5Mhz rate?"
Not sure if he meant 48 bits per second, per millisecond or per
microsecond.
>
> That's 72Mbps, so you can just manage it with the best WiFi routers out there.
Not so, Wifi are rated at burst data rate, not sustained rate.
Joel Koltner
> On May 12, 2:30 pm, "Joel Koltner" <zapwireDASHgro...@yahoo.com>
> wrote:
>> news:ef81eccf-84e9-497f...@j22g2000hsf.googlegroups.com...
>> On May 12, 4:21 pm, "Joel Koltner" <zapwireDASHgro...@yahoo.com>
>> wrote:> Regular old 802.11g wireless routers will get you >50Mbps; channel
>> bonding
>> > (40MHz occupied bandwidth) gets you up to >80Mbps in the best cases...
>> > which
>> > is just as good as anything you get on 5.8GHz WiFi. (These are all
>> > *average*
>> > throughputs, taken from the "wireless charts"
>> > atwww.smallnetbuilder.com...)
>> "48 bits at 1.5Mhz rate?"
>> there.
> Not so, Wifi are rated at burst data rate, not sustained rate.
Sure, the advertised data rate is something absurd like "300Mbps!" But go
read the link I provided -- the best routers absolutely do better than 70Mbps
*on average*. Obviously the speeds gets reduced as you move further from the
router or have other interferers that reduce SNR, but close-in something like
a Belkin N1 will do the job (see:
http://www.smallnetbuilder.com/content/view/30238/96/) for under $200.
linnix
And you probably want his spartan FPGA to talk ethernet as well.
Joel Koltner
> And you probably want his spartan FPGA to talk ethernet as well.
Yeah... slapping down some gigabit Ethernet reference design is one heck of a
lot easier than slapping down a high-speed wireless router design. If you
look at the reviews, you can see that what often makes the difference between
"solid and fast" vs. "flaky and slow" routers isn't the actual hardware --
which is often very similar, if not identical -- but how much tweaking
occurred in the radio controller firmware. Unless I'm building a radio from
scratch, I'd prefer to let someone else worry about that. :-)
Rich Webb
Apparently not.
linnix
wrote:
Sure, if we are looking for a $200 solutions, we can build multi-TX,RX
radios. We don't have to deal with channels and/or routings as well.
Joel Koltner
> Sure, if we are looking for a $200 solutions, we can build multi-TX,RX
> radios. We don't have to deal with channels and/or routings as well.
Yep. Too bad the O.P. here seems to have disappeared!
john
So, I need customized hardware to do this. Are you guys sure that
there are no chips available to do what I want to do? Any suggestions
or pointers that how should I proceed. I have FPGA generated clock and
data stream . Data is 48 bits wide and I am serially outing the data
at 1.5MHz.
Regards,
John
linnix
So you are dealing with 1.5Mbps. In theory, 5.8GHz 802.11n can
handle it. But with all the overheads of channellings and routings,
it will not guarantee the data rate. Your FPGA would have to talk
ethernet/TCP/IP in this case. You can bump it up with Multi-
Transceivers as another poster suggested, but it will not be cheap.
Your best bet is to do a simple modulation/protocol at 5.8GHz.
Rich Webb
What's the actual required throughput? Could you bring the 48 bits
into a FIFO and send them out at a slower (cheaper, easier to find)
rate?
john
Hi,
Okay , What is the slower , achievable rate? I can try to slow the
data rate down to that value
John
linnix
100Kbps Bluetooth
250Kbps ZigBee
Frank Raffaeli
6 feet? if you can use line of sight, consider optical. You can
serialize your 48 bits (I guess that would be 72 Mbps) and modulate
your optical transmitter with that, de-serialize at the other side.
Why can't you use a wire again?
Frank
linnix
wrote:
My understanding is that the internal data path is 48 bits, but the
serial clock rate is 1.5MHz or 1.5Mbps. Either way, he need a custom
solution. If I am right, it would be a cheap custom solution. If you
are right, it would be an expensive custom solution.
Frank Raffaeli
Yep, it looks like 1.5 Mbps as you said. I wonder why no wires? 6 feet
looks like such a short range for wireless, especially RF wireless.
Since it's apparently only 1.5 Mbps, I'd consider something simple,
like FM carrier at 2.4 or 5.8 GHz, Manchester coded. That would double
the BW, but improve the SNR. It's still cheap and simple. I'd publish
a 1.5 Msps demodulator in Verilog for the right kind of beer ;-). The
up/downconverter is up to the OP.
Frank
RFI-EMI-GUY
He says he is "serial outing the data ay 1.5 MHz" . He needs to explain
better what he is doing or intends to do. Otherwise this thread is a
"waste of bandwidth".
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."
"Follow The Money" ;-P
linnix
> > > Why can't you use a wire again?
>
> > > Frank
>
> Yep, it looks like 1.5 Mbps as you said. I wonder why no wires? 6 feet
We need the OP back for sure. If he is really from Wayne State
University Medical Center, perhaps isolation issues from the operating
room?
john
Hi,
I am looking for a digital design or technique that I can use to
transmit the 48bit of data at 1.5MHz frequncy wirelessly. So, what I
gathered so far is that a digital frequncy modulator can be made using
a FPGA and the demodulator can also be made using FPGA. Am I right ,
if yes then i need more guidance , some literature to understand
exaclty how can I do this? The thing that I do not still understand
that If I am right about the FPGA based frequency modulator and
domodulator then how would I design the wireless part of the system?
John
linnix
> Hi,
>
> I am looking for a digital design or technique that I can use to
> transmit the 48bit of data at 1.5MHz frequncy wirelessly.
So, is it 1.6Mbps or 48x1.5=72Mbps?
> So, what I
> gathered so far is that a digital frequncy modulator can be made using
> a FPGA and the demodulator can also be made using FPGA.
The modulator/demodulator can be configurated/controlled by the FPGA,
but you need analog RF circuits. You need to be very careful with PCB
layouts. RF PCB layouts are very tricky.
>Am I right ,
> if yes then i need more guidance , some literature to understand
> exaclty how can I do this? The thing that I do not still understand
> that If I am right about the FPGA based frequency modulator and
> domodulator then how would I design the wireless part of the system?
>
First thing is to pick your encoding scheme. Manchester FM sounds
good, as suggested by other posters.
Rich Grise
Haven't you bothered to read any of the dozens of answers you've already
gotten?
This is why people don't like googlies. Do you expect the answers to
just show up on your desk or something? If you ask on USENET, you get
answers on USENET.
Thanks,
Rich
donald
>
> Hi,
>
> I am looking for a digital design or technique that I can use to
> transmit the 48bit of data at 1.5MHz frequncy wirelessly. So, what I
Send 48bits of data at 1.5Mhz is either:
48bits at a time 1.5M times a second.
or
a 1.5Mhz carrier frequency to send 48bits.
Which is it ??
JosephKK
As i come at this reading the whole thread OP is looking for about 1
mile range and three data sources.
john
Each bit of the 48 bit data gets out of the FPGA at the rising edge of
the 1.5MHz of the Clock. I found following two transciever chips
http://www.chipcatalog.com/Datasheet/A1621136395209573B4A7AEFE50273A1.htm
What do guys think? Has anybody worked with these chips before?
John
JosephKK
Get a (better) news client. Even Outhouse Express (Outlook Express) is
ok by comparison. You need to have proper quoting.
Now that is off my chest, I suspect that neither of these chips will
do what you need directly.
The Nordic Semi device seems to be designed around a 100 ms sample
rate.
The fastest data transfer rate of the Micrel is 128 kb/s. Far less
than the speed it comes out of the FPGA.
What is the timing between 48-bit packets from your source again?
Frank Raffaeli
I still don't know the OP's requirement for data rate, it's still
ambiguous; however, I meant to use the FPGA as the 2nd stage down-
conversion and the demodulator both. The whole receiver (all COTS):
1) 5.8 GHz BPF
2) Mini-circuits mixer
3) Fixed L.O. (with amp)
4) IF amp (assume a 1st I.F of about 1.2 GHz)
5) IF filter (e.g. EPCOS) - don't use SAW unless triple-transit ok.
6) ~500 MSPS converter (with at least 1200 MHz BW)
7) FPGA: Cyclone 3, Spartan, Virtex5, etc ...
The above is for 72Mbits/s. If it's only 1.5 Mbps, then it can be a
lot simpler. Step 4,5,6 could be adapted for direct conversion, which
would be cheaper, but lower performance.
Frank
john
Hi,
Its continous transmission no breaks, just unidirectional
communications. So, if I lowered the clock to lets say 500kHz then
nordic and Micrel chips would be ok to work with.
John
linnix
Not enough details (especially the data rate) on your first link.
Can't access your second link.
If you email them to me, I will take a look.
contact me at www dot linnix dot com
john
Hello,
What inofmation do you require? Please let me know.
Regards,
John
linnix
For the first link. I don't think you need the 8051, if you already
have an FPGA.
I can't read the second link, so I can't tell if it's the right chip
or not. If you have the datasheet somewhere, just email me.
JosephKK
I believe your original problem statement was 48bits per word,
transmitting continuously at 1.5 Mb/s. Neither chip will help you.
Your data rate is beyond what can handle. For the Micrel transmitter
you would have to cut the data rate down to 100kb/s. It may be
possible to use the WiMAX Chip but you will now eat batteries.
You should look for 1.5 to 2Mb/s chips for ISM bands, and narrow beam
antennas.
donald
John wrote on 5/12/2008
> Hi,
>
> 48 bits at 1.5Mhz rate?
>
> John
Clear as mud.
Frank Raffaeli
After re-reading some of your posts, it seems clear that your data
rate is 72 Mbps. It would help to know if this is a one-off
(feasibility) or a design project ... Since you already have a Spartan
on the transmit side, you can use it as a modulator (e.g QAM),
followed by an up-converter, and use another FPGA after down-
conversion on the receive side. I think questions about what "chips"
to use for the RF (or optical) section might be more productive after
we know more about the cost / size and power constraints.
Frank Raffaeli
john
Hi,
1.5MHz is the serial clock rate. So, the time period of this clock
will be approx. 66 ns. Now, at each rising edge of the clock, FPGA
puts a bit out and keep it at its output for one clock cycle. So, FPGA
uses 48 clock cycles to output 48 bits. So, according to my guess the
data rate to transmit one 48 bit frame is (66ns x 48 = 32usec)....The
time interval between two consective 48 bit frames can be anything...
I can transmit one after another or can have some delay between them.
Now , I need a wireless system that can transmit and recieve this
data, clock and a synch. I heard that I can use FSK technique to do
this by programming FPGA as modulator and demodulator. or I can
interface FPGA with the some RF chips that can handle this data rate.
So, I am looking into chips. I can lower the data clock to 600kHz.
The chips links that I found are as follows
http://www.nordicsemi.com/files/Product/applications/nAN24-12Software...
http://www.micrel.com/_PDF/micrf501.pdf
John
linnix
This is your internal data clock. You have to buffer the data and
shift out at a lower rate.
> Now , I need a wireless system that can transmit and recieve this
> data, clock and a synch. I heard that I can use FSK technique to do
> this by programming FPGA as modulator and demodulator. or I can
> interface FPGA with the some RF chips that can handle this data rate.
> So, I am looking into chips. I can lower the data clock to 600kHz.
You have to lower it to 128khz for the Micrel chip
john
Hi,
By 128khz, you meant the Data clock frequency. Am I right?
John
Frank Raffaeli
First you say 1.5M clock, 48 bits at 1.5 MHz, then 66nS, It's
difficult to know what you mean.... If you want to call me, I'll help
you sort it out. I can help you if you want (I have the day off), but
I think it will go 100x faster by phone.
JosephKK
wrote:
Sorry if you are unable or unwilling to read the whole thread. It
might make better sense to you then. Not that it is all that clear in
the first place. OP has been given several offers of professional
advice (probably paid for). I have no idea if OP has pursued them.
JosephKK
wrote:
>JosephKK wrote:
You got it. OP does not seem to understand what the actual
requirements are.
David L. Jones
> Clock, Data and Tag ) stream for a DAC. I need to make this system
> work with out wires. The main clock is 3MHz, Data clock is 1.5MHz. Can
> anybody advice me how to make it digital wireless ( Transmitter plus
> receiver). I have not done anything like this before. The DAC will be
> at 6 feet away from the Spartan chip.
>
> Thanks
> John
Looking at this differently...
Is there perhaps a *smarter* system level way for you to achieve the
same end result?
i.e. do you have to actually output that amount of data continuously
to the DAC via the wireless interface?
Does the DAC output anything repetitive that you can automate on the
receiver side? e.g. if it's say for example a sine wave bust, can you
send a short "generate sine wave burst" "command" instead of the huge
amount of actual DAC data itself?
Dave.