wireless

[john]

Hi,

I build the device with 64 constant current sources . The device has
following specifications

1. 0 to 1mA current bipolar.
2. compliance voltage +/-15 volts
3. Frequency 100 to 1 khertz

I isolated the current sources with tranformers of follwing specs.

primary inductance : 5H
Secondary inductance : 5H
Turn ratio: 1 : 1

So, the load impedance connected across the secondary reflects back to
primary. The device is working good. But now, according to new needs,
I have to make it wireless. The things that are confusing me are
following

1. What do I exactly need to make the system wireless, Do I need a air
core transformer?
2. If all current sources generating the output at same frequncy then
how the receiving end will properly get tune d for it. For example if
current source #1 generates a sine wave of 200hz and another current
source is generating triangular wave of 500Hz does it then isn't there
a chance that the receiving end might catch wrong signals.

Please advice!
John

 

[Bob]

Hi,

I build the device with 64 constant current sources . The device has
following specifications

1. 0 to 1mA current bipolar.
2. compliance voltage +/-15 volts
3. Frequency 100 to 1 khertz

I isolated the current sources with tranformers of follwing specs.

primary inductance : 5H
Secondary inductance : 5H
Turn ratio: 1 : 1

So, the load impedance connected across the secondary reflects back to
primary. The device is working good. But now, according to new needs,
I have to make it wireless. The things that are confusing me are
following

1. What do I exactly need to make the system wireless, Do I need a air
core transformer?
2. If all current sources generating the output at same frequncy then
how the receiving end will properly get tune d for it. For example if
current source #1 generates a sine wave of 200hz and another current
source is generating triangular wave of 500Hz does it then isn't there
a chance that the receiving end might catch wrong signals.

Please advice!
John

It sounds like you need to go back to whoever asked you to make
it wireless, find out exactly what they want, then work
out if it is possible.

What distance does it need to work over?
Is the distance going to vary?

An air core transformer will work very poorly at 100-1000Hz to
start with (unless it is rediculously large).
If the two windings are more than millimeters apart the
loss through the coupling will be very large.


Bob

 

[john]

Hi,

Q. What distance does it need to work over?

Distance will be about seven feet.

Is the distance going to vary?
No


Regards
John

 

[Bob]

Hi,

Q. What distance does it need to work over?

Distance will be about seven feet.

Is the distance going to vary?
No

Regards
John

I still get the feeling that you are not telling us the full
story here.

You need around a watt of peak output maximum in total
for all your channels.
The power transfer efficiency of any wireless scheme over
anything more than millimeters is low to very very very low.

You need a receiver with it's own power source be it a battery
or local power.

You can't send lots of different signals at 100-1000 hertz
through the air and have them arrive seperatley.

Is that frequency range the fundamental frequency of your
waveforms or the band containing all the signficant energy?
EG a 100HZ square wave could contain energy at
gigahertz frequencys if the edges rise and fall very quickly.

You will have to do constant current regulation at the receiver.

If you want to turn individual channels on and off then I'd look
at pair of UHF data transmitter and receivers modules sending
on/off information as a serial stream plus a microcontroller
and some driver chips. This is assuming you generate
your waveforms at the receiver.

If you want to transmit 64 independant arbitary waveforms
wirelessly then it will get interesting just due to the number
of channels but it would be practical to have 64 8bit ADC's
sampling at a few Ksample/sec, an gate array to jam
the sample into one serial stream. That's only 2Mbit/s,
an optical link could carry that without much trouble.
8bit sampling would not give you much range for varying
the level.

Bob

 

[john]

Hi,
Q.Is that frequency range the fundamental frequency of your
waveforms or the band containing all the signficant energy?

Yes

If you want to transmit 64 independant arbitary waveforms
wirelessly then it will get interesting just due to the number
of channels but it would be practical to have 64 8bit ADC's
sampling at a few Ksample/sec

I am using 32 channel output voltage DAC ( AD5532HS ). The DAC works
on
Data, Tag and Data. What if I just buld a wireless digital three line
interface.
Any recommendations that how to do it!

John