DTV antennas?

Certainly a lot better than nothing, but with relatively little infrastructure remaining, 1200bps (and effectively perhaps half the speed of a 1200bps dial-up connection), and few Internet gateways available, realistically I don't think it's of that much use anymore.

Many of the hams who still serious about providing digital support emergency communications (emcomm) are going the D*Star (ham standard) or APCO-25 (public service agency standard) route. Both can easily run regular old TCP/IP, so all the applications one is used to running on their PC over the Internet still work just fine... just a bit slower. (D*Star at 1.2GHz is 128kbps, which is entirely usable even for a bit of web surfing if need be.)

Agreed; AMFM radios are a better bet.

Done stuff like that as well. But then you need to set up an elaborate array of mirrors. Or a web cam if you have a newfangled Internet-capable cell phone.

Those are all just wideband detectors. Wouldn't be that useful for TV bands.

I guess it depends on the area. This is what the Walmart clerk literally told me on the phone: "When the truck unloads you'd have to be here within minutes. They fly off the rack like hot cakes". I can't get there this fast without a major speeding ticket.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Hmm... so I wonder where all those healthcare dollars are going then, if not into "technology..."

You know the problem with the THERAC wasn't so much that it had design flaws, but that the designers refused to admit this might be the case and engaged in denial and resistance for so long.

Yep. The RF has to squeeze through a valley east of the Bass Lake grade.

It's real multipath. On the analog signals you can see ghosts arriving not just tens of usec later but several lines later. Before moving here I didn't think that was possible and still get a good sync.

Can't place the antenna high up, we have a runway next door.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

It's blown on bureacracy, just like with schools. Case in point: We visited an elderly woman at a hospital. During the visit she indicated she needed the bed pan. So I asked at the nurse's desk where somehow there are always lots of nurses typing up stuff on computers (seems rather inefficient to me). Nurse A: "I am busy", I'll call nurse B. She came but she again deferred to nurse C. When nurse C arrived it was too late and they had to change the bedsheets. The system is definitely not efficient.

In a well run company that's not possible. Every incident must be logged and handled within a given time frame. The FDA gives that time frame and it usually means you've got to drop everything and get on it right away. The FDA might waltz in at any time and audit this complaint handling system. So we treated that as a crown jewel and with great respect.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Look at it as another market for $500 USB spectrum analyer boxes. ;-)

I was out the Medford, OR Circuit City yesterday and then had at leat 50 sitting around. I'm surprised there's (still) the kind of demand you're seeing down in Cali!

Ok, but all that matters is a simple message to get through. "Joel Koltner and family safe outside fire zone" takes very little data volume. In a big disaster they'll quickly develop code like "joel koltner +f sofz", even less data volume.

But a good old one, not these button-press thingies from the Dollar store.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

who've

as

to

know

figure

No idea about the dough, my wife makes that. Kneaded in the bread maker, then into the fridge. A couple hours before use it comes out and is formed into two loaves, then onto doubled-up aluminum foil which is lightly sprayed with PAM, which in turn sits on a 50mil steel plate. In the oven, not to bake but to protect it from our dogs.

One starter chimney load of charcoal is all we ever need to cook. Bottom vents fully open steel sheet with bread onto grill, lid on top with vents abour 70% closed. 15 mins later bread is turned around. Another 10 mins later -> done. Standing downwind is torture, like standing in a bakery when fresh bread is brought in. While the bread cools down I cook dinner on the Weber, same set of coals.

Disclaimer: Do this at your own risk. I don't know about any health issues. But it sure tastes good. Just had four slices for lunch, two rye and two wheat. We found that it can be kept in the freezer nicely so we make more than we eat that night, good for hearty lunches. Thing is, we like German style hard-crust bread and you can't buy that out here. It'll take a few runs until you have adjusted the heat and all to your taste. After 5-6 sessions we had it down.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

I believe there are a clump of towers over by Franklin, about 10 miles south of Sacramento. Is that where you show them?

How does your model show Grass Valley (95945) about a quarter mile south of Grass Valley Airport (Nevada County Airpark)? The 3000' MSL contour runs right through the back yard.

Jim

-- "It is the mark of an educated mind to be able to entertain a thought without accepting it." --Aristotle

There's a clump of stations in downtown Sacramento (~28 mi, probably building tops?, and somewhat lower power in the 50kW ranges), but I did not look at every station. Another clump of stations is further south near Walnut Grove ~41 mi., and these are generally more powerful stations (but again, this is not an exhaustive study).

I ran quick profiles and in BOTH cases, you seem to have siginficant terrain obstructions within two miles of Cameron Park. This is not good. :((

Story goes about a new minister that was making his first hospital rounds. Elderly woman in bed, the preacher asks, "How long is it since you've been bedridden?" Little old lady thinks and then says, "My dear husband died about seven years ago..."

{;-)

Jim

I didn't see the towers by Franklin. Perhaps they are not TV. (?) You did not specify which stations you were intereted in, so I'll limit the following to the major networks.

First up: KCRA TV-3 DTV=3D35 NBC Affiliate

596 MHz, 1000kW, Non-Directional Antenna 463 Meters Above Mean Sea Level at Lat=3D38-14-50, Lon=3D-121-30-03 Path Length =3D 71.9 Mi @ 201.5 deg true.

Results: PATH OBSTRUCTED approx 2.5 mi out. at Lat=3D39-11-01.59 Lon=3D-121-01-58.3 Path Clearance =3D -173 feet. (0.5 Fresnel is about 50' greater than this value.)

Notes: KCRA has a Construction Permit (CP) to go to 581 meters AMSL on a nearby tower, but this won't help the situation any. New Coords: 38-15-54, -121-29-24 Channels 3, 35, 43 and 13 are all licensed to the same, (current) tower, by the way. Of these, 43 is a new DTV @ 50kW, and 13 is a new standby station for KOVR (CBS Affiliate)

=3D=3D=3D=3D=3D=3D=3D=3D Next: KOVR-13 DTV=3D25 CBS Affiliate

536 MHz, 760 kW, Non-Directional Antenna 594 Meters Above Mean Sea Level at Lat=3D38-14-24, Lon=3D-121-30-03 Path Length: 72.37 mi @ 201.39 degree true.

Results: PATH OBSTRUCTED approx 2.5 mi out. at Lat=3D39-11-00.5, Lon=3D121-01-58.39 Path Clearance =3D -152 feet. (0.5 Fresnel is about 50' greater than this value).

Notes: KOVR has an application pending to increase power to 1000kW @

615 meters AGL, which will not improve the situation very much. Tower is shared by KXTV-10 (ABC Affiliate)

=3D=3D=3D=3D=3D=3D=3D Next: KXTV-10 DTV=3D61 ABC Affiliate

752 MHz, 1000kw, Non-Directional Antenna 594 Meters Above Mean Seal Level at Lat=3D38-14-24, Lon=3D-121-30-03 Path Length =3D Same as above.

Results: PATH OBSTRUCTED. Same as KOVR above, as this appears to be a shared antenna. KXTV has a Construction Permit to move back to Ch-10 with 22kW @ 613 meters AMSL with a circularly polarized antenna.

=3D=3D=3D=3D=3D=3D Finally, KTXL-40, DTV-55 Fox Affiliate

716 MHz, 1000kW, Directional Antenna (triangular shaped with major lobes at 20, 140 and 260 degrees true, side nulls at 66% relative field power to main beams) 582 Meters Above Mean Sea Level at Lat=3D38-16-18, Lon=3D121-30-18 Path Length =3D 70.4 miles @ 202.2 degrees true

Results: PATH OBSTRUCTED approx 2.5 mi out at Lat-39-11-03.13, Lon=3D-121-01-59.6 Path Clearance =3D -175 feet (0.5 Fresnel is -263 feet)

Notes: KTXL has a Construction Permit to move to Ch-40, 1000kW, @ 601 meters AGL with a Directional Antenna. Pattern will be peanut shaped with major lobes at 20 and 140 degrees true, null at 60% relative to main beams. Very little power to the west.

KTXL has an Application to reduce power on CH-40 to 950 kW and revert to the triangular shaped pattern with major lobes at 10, 130 and 250 degrees true, again with side nulls set at 66% relative field.

CONCLUSION: In short, there is a ridge approx 2.5 miles S-SW of your position that sits between you and the above (4) network stations. The obstruction appears late in the path, approximately 70 miles (+/-) from the transmitter sites. Both the line-of-sight, and one half of the first Fresnel Zone ellipse are completely obstructed by at least 150 feet, not counting vegetation, etc...

You would likely need at least a 200 tower to overcome LOS obstructions.

-mpm

I didn't mention it, but these calculations were made from the intersection of Grenhorn Road and Kantoberry Court, using a MSL of

2839 feet, and an outdoor antenna mounted at 30 feet off the ground.

39.217891

-121.01556

That's the problem. We sit halfway between Greenhorn Road and Loma Rica Road just south of Grass Valley Airport. You've chosen a ground site that's

160' below our elevation. Lat Long here is 39d 13.0224' -121d 0.5272'

If you are looking for ground coordinates, go half a mile out Greenhorn Road from Brunswick. There is a road taking off to the south called Hollydale. Directly across Greenhorn from Hollydale is Downwind Court. Go all the way to the end of Downwind Court and then another 75' due north. That's us.

Kantorberry Ct. is a good half mile out Greenhorn PAST us and at least another 160-200' down.

Jim

--
"It is the mark of an educated mind to be able to entertain a thought 
without accepting it."
        --Aristotle


"mpm"  wrote in message 
news:3860d226-f2b2-4b68-bf1c-cc41794ee05f@d1g2000hsg.googlegroups.com...
On Jul 14, 6:58?pm, mpm  wrote:

I didn\'t mention it, but these calculations were made from the
intersection of Grenhorn Road and Kantoberry Court, using a MSL of
2839 feet, and an outdoor antenna mounted at 30 feet off the ground.

39.217891
-121.01556

Not to be argumentative, but those towers you reference are NOT in downtown Sacramento, but legally within the town of Walnut Grove, just a skip above Franklin. See here:

I'm not sure if the latlongs you gave were for the Walnut Grove site or for the studio site(s) downtown.

Jim

-- "It is the mark of an educated mind to be able to entertain a thought without accepting it." --Aristotle

I didn't see the towers by Franklin. Perhaps they are not TV. (?) You did not specify which stations you were intereted in, so I'll limit the following to the major networks.

wn

e

or

I did not claim the (4) networks in my second email were downtown. (??) In fact, I didn't say where they were, other than provide their exact transmitter coordinates. Obviously, given the mileage calculations, they cannot possibly be downtown, as you correctly note.

The coordinates provided are for the transmitter site(s), not the studios.

But to your point, if your AMSL is 150 greater than that studied, it should help a little. How much is hard to say. You're right on the edge of line-of-sight coverage 70 miles out. That's a very, very narrow angle - which would not change appreciably, even with the extra height. It's too bad you're not up another 100 feet or so!! But in this case, I would say every little bit helps.

)

Even looking out four miles from Franklin, I don't see any broadcast towers licensed. There are (7) towers total. Actually, 5 towers and 2 poles. These are registered to: Nextel, Verizon, PacBell, 2 for Cingular, Sacramento Valley LP, and one that appears to be a private residence. Weird.

I do see all the towers down in the Walnut Grove area. Maybe those are the ones you're thinking of? I wonder if Google Maps has fine enough detail for Franklin..?

-mpm

Converting to something I can plug into Radio Mobile, that's: 39.21704N -121.00088W Please verify the location.

I ran a path profile using Radio-Mobile 9.2.0 to KCRA Ch 35 DTV at: 38.24722N -121.5008W

It's kinda hard to see the problem but your house (identified as RST) is well below a nearby hill. That's not going to work.

I think I have the tx power and antenna characteristics correct, but I'm having a bit of trouble untangling the rx sensitivity for ATSC. I'll add the original work files to the above directory when I RTFM and/or figure it out.

Bug me if you want more detail, the original files, or path to another DTV xmitter.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Consumer kit made down to a price (and then some more shaved off).

That tends to suggest that signal levels are an issue.

There may be. Worth looking for the engineers manual for whatever kit you have got. I find it hard to believe that the Japanese manufacturers downgraded their kit to remove basic utility features for the US market. OTOH the Panasonic ATSC kit I saw reviewed recently seems to still be missing fundamental features...

It all seems to point back to the dodgy US trial of COFDM which was designed to fail leading to 8VSB being adopted. The only time congress actually looked at working kit saw that COFDM outperformed 8VSB. eg

Some of the ATSC PC cards being reviewed now appear to have the sorts of signal measurement features I expect to see - for example:

It might be worth investing in one of them and a toy aerial for experiments rather than fighting with kit up on the roof...

That is a whole different ball game. You have moved the goal posts.

You might be able to make some headway by putting an earthed fine mesh reflector hung off the yagi on the runway side. Then you get a mirror boundary condition and hide the aircraft. A fixed local strong reflection will look like a pair of aerials but with a bit of luck containing less of the unwanted runway reflection signal.

Airports tend to have lots of angular metallic structures moving around so you are in a pretty tricky location.

Thats certainly an option.

Regards, Martin Brown

** Posted from **

Can't you buy one online from one of the electronics dealers?

The what??? In "socialist" Britian you would have to prove you were absolutely destitute to get a subsidy on a digital set top box!

ISTR there is a scheme to make them available free to pensioners. And more importantly some help in setting the thing up to work. The older TV aerials lacked the right characteristics and often needed replacing for DTV.

Incidentally over here a few early adopters have come unstuck when the latest signal encoding improvements have broken the earliest firmware. It is estimated that about 1% of all set top boxes sold to date will fail as a result (although most early adopters probably have replaced it by now). At present only a few parts of Scotland are affected.

Regards, Martin Brown

** Posted from **