2 Sep
2017
2 Sep
'17
12:32 p.m.
A couple of decades ago, the "GRAPES" WA4DSY
56kbit modem kit was
available for a moderate price. They weren't too difficult to put
together. Alignment did take a scope, but took only a few minutes. About
five people in San Diego had them. As far as I know, only three ever
made it onto the air here.
I remember that modem, but also I remember that there were quite some issues at that
time.
It was not easy to reliably make 56k HDLC using affordable hardware at that time.
For interrupt-per-character serial devices the performance of a PC-XT was not quite
enough.
There were DMA-based controllers but they were difficult to obtain, hard to find reliable
drivers for, and expensive.
Some people built 68000-based boards for that kind of datarate, and later for 1-2Mbps,
also
using DMA. I also considered using PC-LANA adapters that had all the data generating hw
as a co-processor but were not AX.25 compatible. (they use the NETBIOS interface, I
added
IP over NETBIOS to my version of NET to be able to use them)
However, no real radio link has ever been made here.
Of course wide acceptation would have been even more difficult.
Today, the computer performance problem no longer exists, but the problem of wide
deployment
of a locally designed solution still exists.
Rob
2 Sep
2 Sep
1 p.m.
New subject: OFDM Modem
On 2017-09-02 09:32 AM, Rob Janssen wrote:
We used the PI2 card here at UBC, using the original pi driver and then
the dmascc driver once it was available. It was a bit of a fiddle to
find a clear IRQ/DMA on crowded machines but dedicated router boxes (an
old XT worked) were pretty stable. Losing ISA slots on newer computers
meant that we were limited to older systems.
With two local mountain top repeaters on UHF (using custom duplexors) we
had a handful of users over 70-80 km paths ... kept my dad online for
several years before cables modems made it to the farm :)
Eventually the remaining users lost interest and I gave up after the
last repeater went down. At $800-1000 for a working system it just
didn't get enough people to sustain itself, and cheaper broadband meant
many of the original users didn't find it worthwhile.
Still have two repeaters worth of gear cluttering up my storage, hard to
let go of a project that took so much of my time !
... Niall
A couple of
decades ago, the "GRAPES" WA4DSY 56kbit modem kit was
available for a moderate price. They weren't too difficult to put
together. Alignment did take a scope, but took only a few minutes. About
five people in San Diego had them. As far as I know, only three ever
made it onto the air here.
I remember that modem, but also I remember that there were quite some
issues at that time.
It was not easy to reliably make 56k HDLC using affordable hardware at
that time.
For interrupt-per-character serial devices the performance of a PC-XT
was not quite enough.
There were DMA-based controllers but they were difficult to obtain, hard
to find reliable
drivers for, and expensive. 
1:15 p.m.
New subject: old gear [Was "OFDM Modem"]
On Sat, Sep 02, 2017 at 10:00:19AM -0700, Niall Parker wrote:
Still have two repeaters worth of gear cluttering up
my storage, hard to let
go of a project that took so much of my time !
... Niall
Yes, I have a pile of old electronics stuff in my garage too. I realized
the other day that it will cost more to have the junk man haul it away
than it's worth, so until I need the space for something else, there
it sits. I have a box of TAPR TNCs, for example. They all need new
batteries by now. Nobody wants them. And the old Motorola repeater
gear is HEAVY. It's getting painful to lift. It doesn't sell on Ebay.
It's just that I worked so hard in obtaining these things in the first
place that it's hard to let go.
- Brian
10:41 p.m.
New subject: old gear [Was "OFDM Modem"]
On 3/09/2017 8:49 AM, vk2tv wrote:
Yeah, know that feeling. I've got a shed full
of old junk that's
probably now better suited to the e-waste recyclers. :)
--
73 de Tony VK3JED/VK3IRL
http://vkradio.com
It's just that I worked so hard in obtaining
these things in the first
place that it's hard to let go.
- Brian
_
Isn't that a familiar line? 
3 Sep
3 Sep
11:07 p.m.
New subject: Old Gear [Was "OFDM Modem"]
On Sun 3 Sep 2017, Tony Langdon <vk3jed(a)vkradio.com> wrote:
>On 3/09/2017 8:49 AM, vk2tv wrote:
> Brian Kantor wrote:
>> It's just that I worked so hard in obtaining these things in the first
>> place that it's hard to let go.
>> ????- Brian
>
> Isn't that a familiar line?
Yeah, know that feeling. I've got a shed full of
old junk that's
probably now better suited to the e-waste recyclers.
Tony,
By any chance, do you know the names, model numbers, and capabilities
of the items in your shed off the top of your head? I'm just curious:
I'm thinking of starting an old junk museum and I'll need donations. ;-)
73,
Bill, W4EWH
11:11 p.m.
New subject: Old Gear [Was "OFDM Modem"]
The theme song to Sanford and son is rolling through my head from that last comment.
Best,
Elias
Sent from my iPhone
On Sep 3, 2017, at 10:07 PM, Bill Horne
<bill(a)horne.net> wrote:
On Sun 3 Sep 2017, Tony Langdon <vk3jed(a)vkradio.com> wrote:
> On 3/09/2017 8:49 AM, vk2tv wrote:
> Brian Kantor wrote:
>> It's just that I worked so hard in obtaining these things in the first
>> place that it's hard to let go.
>> ????- Brian
>
> Isn't that a familiar line?
Yeah, know that feeling. I've got a shed full
of old junk that's
probably now better suited to the e-waste recyclers.
Tony,
By any chance, do you know the names, model numbers, and capabilities
of the items in your shed off the top of your head? I'm just curious:
I'm thinking of starting an old junk museum and I'll need donations. ;-)
73,
Bill, W4EWH
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4 Sep
4 Sep
12:53 a.m.
New subject: Old Gear [Was "OFDM Modem"]
On 4/09/2017 1:07 PM, Bill Horne wrote:
Tony,
By any chance, do you know the names, model numbers, and capabilities
of the items in your shed off the top of your head? I'm just curious:
I'm thinking of starting an old junk museum and I'll need donations. ;-)
Unfortunately no, such organisation is not my strong point.
--
73 de Tony VK3JED/VK3IRL
http://vkradio.com
2448
days inactive
2450
days old
8 comments
8 participants
participants (8)
-
Bill Horne -
Brian Kantor -
Elias Basse -
Kathie Dart -
Niall Parker -
Rob Janssen -
Tony Langdon -
vk2tv