USB (the other one!) A2D converters?
 

Does anyone have experience and/or recommendations
for analogue and digital I/O interfaces based on the Universal
Serial Bus (USB)?

Just an idea for the genesis of a homebrew spectrum analyser.

USB (the other one!) A2D converters?
 

Does anyone have experience and/or recommendations
for analogue and digital I/O interfaces based on the Universal
Serial Bus (USB)?

Just an idea for the genesis of a homebrew spectrum analyser.



I can't give any specific advice about the USB interface, but I recall that
there was a PC based spectrum analyser published in QEX within the last
couple of years.

If you don't already, I would recommend subscribing to QEX, it's published
quarterly by the ARRL. It contains a lot of leading edge technology. A
Google search will give you more details.

USB (the other one!) A2D converters?
 

On Jul 28, 3:59 am, "G \"Guglielmo\" Evans G4SDW"
wrote:
Does anyone have experience and/or recommendations
for analogue and digital I/O interfaces based on the Universal
Serial Bus (USB)?

Just an idea for the genesis of a homebrew spectrum analyser.

Ive done a little with USB, so I'll add a little background if not
provide complete answers.

The first hurdle is the interfacing. You need a board with a driver
thats easy to interface with your host PC software program.
Ive used a board from www.mirrorbow.com for general control...you can
access it every 1mS and get 12 x 12bit ADC samples for each access, or
you can alter 8 bit digital ports etc. However, the speed is limited
to how fast the operating system can access the board, which is 1mS.
This board pretends to be a com port so it makes programming easier
without needing to include libraries and dlls etc.
Theres a board from National Instruments which I think is faster,
though only around 2.8Msamples/sec http://sine.ni.com/nips/cds/view/p/lang/en/nid/202596
And of course there are some dedicated USB spectrum analyser
available, but thats not the same as doing a home version.
So, you could just get a DAC board and go for it, though the speed you
can make a spectrum analyser is limited.

Of course you could use the superhet principle with a narrow band
filter and a programmable LO. You could then use a simple IO board
like the one from Mirrorbow to setup the LO, then use a peak detector
and the boards AD to give an indication of level. You'd then have a
digitally controlled analogue spectrum analyser, and you woudlnt need
the large sample rate.

USB (the other one!) A2D converters?
 

mirrorbow is not a bona-fide operation and does not advertise its
address, directors and other information as now required
by UK law.

"bigorangebus" wrote in message
ups.com...

The first hurdle is the interfacing. You need a board with a driver
thats easy to interface with your host PC software program.
Ive used a board from www.mirrorbow.com for general control.

USB (the other one!) A2D converters?
 

The jobless bar steward wrote:

mirrorbow is not a bona-fide operation and does not advertise its
address, directors and other information as now required
by UK law.

Well, why don't you e-mail them and tell them what you read in your £350 law
book. There are two e-mail addresses on their website. I'm sure they'd be
delighted to hear from you as much as we are.

Better still, GET A JOB.

USB (the other one!) A2D converters?
 

"John" wrote in message ...

Does anyone have experience and/or recommendations
for analogue and digital I/O interfaces based on the Universal
Serial Bus (USB)?

I can't give any specific advice about the USB interface, but I recall
that
there was a PC based spectrum analyser published in QEX within the last
couple of years.

The state of USB has improved pretty dramatically in the past couple of
years. The QEX article was a groundbreaker at the time, but the technology
has moved on.

Presumably you are aware that a USB interface implies computation on both
sides. The relatively recent USB PICs (18F2550, 4550, etc.) incorporate
everything needed for the USB interface except the connector. Only a couple
of years ago a USB controller chip was $26 and it needed a host of
additional parts to actually implement the interface. A smaller USB PIC
costs less than $5 and includes *everything*.

Go to http://ww1.microchip.com/downloads/e...Doc/39632D.pdf and take a
look at the capabilities. To see it in an actual circuit, try
http://www.microchip.com/stellent/id...ame =en529760
and download the users guide. The 2550 is the little TQFP to the right of
the board picture, although it is available in a variety of packages, some
more hobbyist-friendly then the tiny one on the board. The only additional
part is an inductor to filter the USB voltage when it is used to power the
target circuit.

This series of parts also includes A/D channels, tho they might not be the
speed and resolution you want. The particular board is a nice one for
experimenting because it includes one of the fast 16-bit parts that are
easily programmable in a high level language, along with the USB interface.

...

USB (the other one!) A2D converters?
 

"xpyttl" wrote

Presumably you are aware that a USB interface implies computation on both
sides. The relatively recent USB PICs (18F2550, 4550, etc.) incorporate
everything needed for the USB interface except the connector. Only a
couple
of years ago a USB controller chip was $26 and it needed a host of
additional parts to actually implement the interface. A smaller USB PIC
costs less than $5 and includes *everything*.

Go to http://ww1.microchip.com/downloads/e...Doc/39632D.pdf and take
a
look at the capabilities. To see it in an actual circuit, try
http://www.microchip.com/stellent/id...ame =en529760
and download the users guide. The 2550 is the little TQFP to the right of
the board picture, although it is available in a variety of packages, some
more hobbyist-friendly then the tiny one on the board. The only
additional part is an inductor to filter the USB voltage when it is used
to power the target circuit.

This series of parts also includes A/D channels, tho they might not be the
speed and resolution you want. The particular board is a nice one for
experimenting because it includes one of the fast 16-bit parts that are
easily programmable in a high level language, along with the USB
interface.



Many thnaks for the heads-up on the PICs. I've always tried to avoid USB
interfaces for control applications, but I have a project on the horizon
where I will almost certainly go down that route - simply because laptops no
longer have RS-232 ports..

USB (the other one!) A2D converters?
 

"John" wrote in message ...

Many thnaks for the heads-up on the PICs. I've always tried to avoid USB
interfaces for control applications, but I have a project on the horizon
where I will almost certainly go down that route - simply because laptops
no longer have RS-232 ports..

If this is a one-off project, you might even consider that particular board,
depending on your requirements. The USB is used as a peripheral to the 28
pin part, so that from the bigger part you can simply do a printf() to
communicate to your PC over serial. It relies on a Microcoft provided
serial emulation driver. If your requirements are more demaiding, then you
will need to really hit the books. Doing the USB software interface isn't
real trivial.

...

USB (the other one!) A2D converters?
 

"xpyttl" wrote in message
...
pin part, so that from the bigger part you can simply do a printf() to
communicate to your PC over serial. It relies on a Microcoft provided
serial emulation driver. If your requirements are more demaiding, then
you will need to really hit the books. Doing the USB software interface
isn't real trivial.

mmmm ... I can see I should have been more explicit there, and maybe caught
a couple of typos.

There are a number of USB classes with different capabilities. There is a
serial emulation class, which Microsoft provides a driver for. It appears
on Windows as a new serial port, and applications access it as if it were a
serial port.

All USB devices must offer up a manufacturer code and a device code whenever
they are first connected. The OS reads a .inf file to connect the
particular codes to a driver. MicroCHIP provides an .inf file with the
board that points to a MicroSOFT driver which does serial emulation.

When the 16-bit part wiggles it's USART, the PIC18F2550 catches that and
sends it out over USB to the PC in serial emulation mode. The application
on the 16 bit part must set up the baud rate for the USART, but beyond that,
normal C I/O can be used, although it is pretty fat for many applications.

The documentation for the board says in comes with a dsPIC33FJ12GP202 but
mine came with a PIC24FJ64GA002 -- more memory but no DSP engine. The board
has jumpers to accept any 28 pin, 16 bit part. I've been doing most of my
experimentation with a dsPIC30F012. The 30F parts are 5 volts, the others
3.3, and the 30Fs have a slightly different pinout. Jumpers deal with both,
as well as deciding whether the board wants to be powered from the USB or a
separate supply.

For a lower cost implementation, the 18F2550 and its cousins have plenty of
gas to do more work, and Microchip does provide sample code for the USB
serial interface, but I've always been a bit suspicious of Microchip sample
code ... often it isn't quite as solid as one would hope.

...

USB (the other one!) A2D converters?
 

"John" wrote in message ...
Many thnaks for the heads-up on the PICs. I've always tried to avoid USB
interfaces for control applications, but I have a project on the horizon
where I will almost certainly go down that route - simply because laptops no
longer have RS-232 ports..

Many products still use RS-232 (albeit at TTL voltage levels) internally and
just use, e.g., an FTDI USB--RS-232 converter chip (such as the FT2232R).
This is actually easier than using a USB microcontroller, although it does
tend to end up being a little more expensive as well (i.e., $5 for the FTDI
IC, $5 for a microcontroller vs. $5 for a USB controller).

USB (the other one!) A2D converters?
 

"G "Guglielmo" Evans G4SDW" wrote in message
...
mirrorbow is not a bona-fide operation and does not advertise its
address, directors and other information as now required
by UK law.

That is a little odd. Any idea why they aren't more forthcoming?

USB (the other one!) A2D converters?
 

"G "Guglielmo" Evans GW4SDW" wrote in message
...
Does anyone have experience and/or recommendations
for analogue and digital I/O interfaces based on the Universal
Serial Bus (USB)?

Just an idea for the genesis of a homebrew spectrum analyser.

Next consideration....not having to hand any components or
experience of the broadcast TV band (0.4 - 1GHz?) I wonder
what tuners and mixers are fitted to modern TVs and if anyone
can recommend a tuner separate from a main board that
might be used.

Also, where tuners are driven by I2C and similar busses, are
they channelised to fit the standard TV channels, or do they
have a delta frequency, say, 10kHz, that might be useful
for a spectrum analyser?

USB (the other one!) A2D converters?
 

"G "Guglielmo" Evans G4SDW" wrote in message
...

"G "Guglielmo" Evans GW4SDW" wrote in message
...
Does anyone have experience and/or recommendations
for analogue and digital I/O interfaces based on the Universal
Serial Bus (USB)?

Just an idea for the genesis of a homebrew spectrum analyser.

Next consideration....not having to hand any components or
experience of the broadcast TV band (0.4 - 1GHz?) I wonder
what tuners and mixers are fitted to modern TVs and if anyone
can recommend a tuner separate from a main board that
might be used.

Also, where tuners are driven by I2C and similar busses, are
they channelised to fit the standard TV channels, or do they
have a delta frequency, say, 10kHz, that might be useful
for a spectrum analyser?

Maybe you could look at tuner boards form an old VCR, On VCR's Circa 1990
the tuners were a separate board, Older tuners were simply fed by a PWM
output from the display / timer CPU that was then fed to an amplifier/
smoothing stage that then gave a 36V down to 2V DC voltage to select
frequency, they were analogue tuners, so not stepped, there was usually
another line to the tuner to disable the AFT lock that was used when
scanning for new channels.
We used to take the VCR tuner board, put it in a box with a PSU, pin the
AFT lock line to 5V to disable AFT then use a 10K pot with a 2K or 3K
fixed R on the 0V leg, the wiper to the collector of the transistor that was
after the PWM input line.
The modules used in the VCR's were usually Mitsumi or Alps, and if you get
hold of an European one. then you can tune VHF and UHF with it, but you will
need to apply 5V to the band switching pins on the tuner. and yes it can be
used as a basic spectrum analyser, but you may have to find a way to disable
the AGC circuits.
Also the tuner boards rely on the RF output modulator / pass though unit on
the back sockets of the VCR having considerable gain, without the
modulator, the signal would be weak.

USB (the other one!) A2D converters?
 

On Jul 30, 6:05 pm, "Joel Kolstad"
wrote:
"G "Guglielmo" Evans G4SDW" wrote in ...

mirrorbow is not a bona-fide operation and does not advertise its
address, directors and other information as now required
by UK law.

That is a little odd. Any idea why they aren't more forthcoming?

I received both the boards I ordered from Mirrorbow in a few days and
all my email enquiries were answered extremely quickly and
thoroughly. I guess they are not a multinational, and Ive never had
cause to ring them. However, payment is via Palpal which I believe
offer a degree of protection anyway. My invoice on delivery had their
address on it.

There are lots of companies online that dont show addresses or phone
numbers online, so I cant believe it is illegal not listing them!
Otherwise all those webspace providers would be breaking the rules!

I think its a silly to post a comment stating that they are not "bona-
fide" unless you can post evidence to suggest this.

Twice I sent my money via paypal, and twice I received my board
quickly and it worked to spec. I had questions, and they were
answered on email.

If we expect every company we deal with as amatuer electronics
enthusiasts to have a call centre and list streams of directors I
think we would find them thin on the ground in our specialist area!

USB (the other one!) A2D converters?
 

On Jul 30, 6:05 pm, "Joel Kolstad"
wrote:
"G "Guglielmo" Evans G4SDW" wrote in ...

mirrorbow is not a bona-fide operation and does not advertise its
address, directors and other information as now required
by UK law.

That is a little odd. Any idea why they aren't more forthcoming?

Oh, by the way, I found them through a magazine article written by a
Davy Dick in a publication called MERG. Which is a model railway
magazine (don't ask!). He's a railway enthusiast and the article was
about using the board for controlling model railways, I don't think he
has any association with the company.

USB (the other one!) A2D converters?
 

"bigorangebus" wrote in message
oups.com...
There are lots of companies online that dont show addresses or phone
numbers online, so I cant believe it is illegal not listing them!
Otherwise all those webspace providers would be breaking the rules!

I think its a silly to post a comment stating that they are not "bona-
fide" unless you can post evidence to suggest this.

The evidence is their web site which does not comply with UK law
as to revealing the business address and names of directors.

USB (the other one!) A2D converters?
 

on 05/08/2007 16:27 bigorangebus said the following:

If we expect every company we deal with as amatuer electronics
enthusiasts to have a call centre and list streams of directors I
think we would find them thin on the ground in our specialist area!

and VERY expensive!
--
;-)
73 de Frank Turner-Smith G3VKI - mine's a pint.
http://turner-smith.co.uk

USB (the other one!) A2D converters?
 

On Aug 5, 4:59 pm, "G \"Guglielmo\" Evans G4SDW"
wrote:
"bigorangebus" wrote in message

oups.com...

There are lots of companies online that dont show addresses or phone
numbers online, so I cant believe it is illegal not listing them!
Otherwise all those webspace providers would be breaking the rules!

I think its a silly to post a comment stating that they are not "bona-
fide" unless you can post evidence to suggest this.

The evidence is their web site which does not comply with UK law
as to revealing the business address and names of directors.

Do you have a web link to information on this requirement? I'm
curious.

How do businesses operate that are partnerships or sole traders? It
is not a requirement for a business in the UK to have directors, so
how can they all be required to show them. You're suggesting you have
to be a limited company (they have directors) to trade on the net....

USB (the other one!) A2D converters?
 

On Aug 6, 5:23 pm, bigorangebus wrote:

Do you have a web link to information on this requirement? I'm
curious.

http://preview.tinyurl.com/2fbnzy

David

USB (the other one!) A2D converters?
 

"David Powell" wrote in message
ups.com...
On Aug 6, 5:23 pm, bigorangebus wrote:

Do you have a web link to information on this requirement? I'm
curious.

http://preview.tinyurl.com/2fbnzy

That applies to limited companies and partnerships. Not sole trader
concerns.



David

USB (the other one!) A2D converters?
 

On Aug 5, 9:04 pm, Cheemag wrote:
On Sun, 05 Aug 2007 08:27:19 -0700, bigorangebus
wrote:

I received both the boards I ordered from Mirrorbow in a few days and
all my email enquiries were answered extremely quickly and
thoroughly. I guess they are not a multinational, and Ive never had
cause to ring them. However, payment is via Palpal which I believe
offer a degree of protection anyway. My invoice on delivery had their
address on it.

There are lots of companies online that dont show addresses or phone
numbers online, so I cant believe it is illegal not listing them!
Otherwise all those webspace providers would be breaking the rules!

I understand that the law in the UK requires that they show at
least an address and telephone number if the website is located
here.

--

73, Jim, G4RGA

Rally Info:http://www.g4rga.org.uk

I didnt imagine putting this very helpful company in my post was going
to create so many problems and I feel a bit guilty now!
I found this on the web:
***************************************
According to Outlaw, the following is the minimum information that
must be on any company's website.

* The name, geographic address and email address of the service
provider. The name of the organisation with which the customer is
contracting must be given. This might differ from the trading name.
Any such difference should be explained ??? e.g. "XYZ.com is the
trading name of XYZ Enterprises Limited."

It is not sufficient to include a 'contact us' form without also
providing an email address and geographic address somewhere easily
accessible on the site. A PO Box is unlikely to suffice as a
geographic address; but a registered office address would. If the
business is a company, the registered office address must be
included.
******************************************

I sent it to mirrorbow and they said they would put an address up on
the contact page http://www.mirrorbow.com/contact.htm so it should be
there by the time people read this. The company is privately owned
and does not have directors apparently, and they said that they didnt
post an address as they do not have the facilities to receive
customers.

I would recommend you email the mirrorbow guys and ask you're
technical questions before ordering. I was impressed by the friendly
help I received.

USB (the other one!) A2D converters?
 

On Aug 6, 5:40 pm, "Paul" wrote:

http://preview.tinyurl.com/2fbnzy

That applies to limited companies and partnerships. Not sole trader
concerns.

Yes - I'm not aware of any equivalent regulations apply to sole
traders or partnerships (other than limited liability partnerships -
LLPs).

David

USB (the other one!) A2D converters?
 

--
Via: http://www.jumlers.com/rec.radio.amateur.homebrew/

If I can throw in my two-penny-worth...

I have dealt with Mirrorbow Electronics, purchased their USB IO
board and it does exactly as advertised. their technical support is
100%, delivery is very quick and overall service is second to none!
I have no hesitation in recommending them to anyone. I only wish
some other companies would take a leaf out of Mirrorbows book for
customer service!

Off my soap box now...

73s, Jason G7KPM