10 Feb
2021
10 Feb
'21
12:19 a.m.
Hi Eric, the lowest 8 bits are just random noise, usually. Takes a very expensive setup
to reduce the noise figure. Low bands are noisy, higher bands less so. Think about
microwaves and avoiding galactic noise sources (Cygnus X-1, Sagg* A)
73, Cliff K6CLS CM87
On February 9, 2021 8:26:28 AM PST, Eric Fort via 44Net <44net(a)mailman.ampr.org>
wrote:
How much deeper could we dig signals out of the noise
if we sampled
32bit samples at 32 mega samples per second then piped it all over ip
for the entirety of TACC to chew on. (Wiki lists TACC as 5th in the top
500)
Eric
Sent using SMTP.
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On Feb 9, 2021, at 6:02 AM, pete M via 44Net
<44net(a)mailman.ampr.org>
wrote:
There is always multiple ways to skin a cat. But
the SDR I talk
about is a transceiver. I know we can use other type of processing
and
less BW. But what is the fun?
Téléchargez Outlook pour Android<https://aka.ms/ghei36>
________________________________
From: 44Net <44net-bounces+petem001=hotmail.com(a)mailman.ampr.org> on
behalf
of Cliff Sojourner via 44Net <44net(a)mailman.ampr.org>
Sent: Monday, February 8, 2021 6:01:48 PM
To: 44Net general discussion <44net(a)mailman.ampr.org>
Cc: Cliff Sojourner <cls(a)employees.org>
Subject: Re: [44net] ASN # and Network Service Provider (NSP)
We already have hundreds of SDRs available via IP. One aggregation
is at
http://websdr.org/
Frankly, sending 50MHz bandwidth at say 16 bits over IP is perhaps
the worst way to
do it... Just to find that elusive 50Hz CW signal!??
The latest SDRs have a massive A/D for baseband capture, perhaps
250MHz,
immediately processed by multiple FPGAs, then perhaps sent to
Gnu Radio on a very fast multicore CPU. This is no simple trick. But
my point is, people smarter than me have figured out it is better to
decimate and process locally, not at the end of an IP connection.
So i am still at a loss for compelling high bandwidth applications.
(Thanks for indulging my detour here. Back to regularly scheduled
BGP etc.)
Cliff K6CLS CM87
> On February 6, 2021 3:54:12 PM PST, Tony Langdon via 44Net
<44net(a)mailman.ampr.org> wrote:
>> On 7/2/21 8:32 am, pete M via 44Net
wrote:
>> We dont have high bandwith application?
>> What about 50 Mb/s ? is that high speed enough?
>> SDR kike the Hermes-Liet 2.0 can feed the HF spectrum to a software
> remotely By IP stream at up to 50Mb/s
>> Would it be a nice thing to have multiple SDR transceiver on
multiple
> bands all over the world available to ham
that run a 44net adress?
> Now that would be neat - having access to SDR IFs remotely, though
> those
> speeds are only going to be available at a regional level if routing
> over the Internet. While I have 80+ Mbps available downstream, that
> really only applies to relatively local (within VK for me)
endpoints.
> Once I'm going overseas, usable bandwidth
can drop to 10 Mbps or
less,
> from end to end. But the 2-2.4 MHz bandwidth
of RTL-SDR class
devices
> might be more practical on an international
scale, which means a
> transport that can scale to suit available bandwidth. Also, for
> latency
> reasons, we would want optimal routing on our core infrastructure,
> which
> ties back to the previous discussion.
>
> Nice out of the box thinking there. :)
>> Would it even be a nice intitative to build an high speed RF
linking
> system for that use case?
> The biggest challenge with high speed RF is cost and complexity.
Not
> everyone is able to build UHF/microwave
equipment reliably. I have
a
> number of issues in that area - some
intrinsic, some are time
related,
> and the cost of high speed/wide bandwidth
microwave equipment tends
to
> be rather expensive, given that amateur
applications tend to be low
> volume, compared to something like mobile phones or wifi.
>> I can think of many more project like that.
>> Most people dont think of such project for a simple reason, most of
> the mode we use are narrow by definition, and since the FCC limit
the
> maximum Bandwith available by bands to a bare
minimum and that the
USA
> ham's must comply to this insane thing,
the rest of the world is
kind
> of being drag to that fact.
>> Just take the New pascket radio project, Canadian hams could use it
> at the maximum spead it was designed for, US, nope 70cm bandwith
limit
> will prevent it. Frustrating I must say.
> I'm pretty sick to death of being held back by archaic US
regulations.
> Here, we can also use whatever bandwidth a
mode requires, provided
we
> stay within the band limits (on VHF and up).
There may be some
> interesting band plan issues on 70cm, but we hams can resolve those.
> On
> 1.2 GHz and up, there's bandwidth to burn, and it would be good to
make
> use of that. :) Maybe the rest of the world
should just get on with
it
> and encourage US hams to lobby to get their
regulations updated to
> match
> the rest of the world, and in the meantime, the US battles on as
best
it
can until they can sort out their regs and join us RF wise.
--
73 de Tony VK3JED/VK3IRL
http://vkradio.com
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