tv antenna

[ajsail1]

im planning to add a tv antenna on the boat this season. My port is beyond 30 miles from the city of chicago where signals are (winthrop harbor). Seawatch literature recommends the 2025 for beyond 30 miles from signals. Do you agree or can I get by with the 2020 and still get good reception? Also i found this ad on ebay for an antenna i never heard of, figured id ask your opinions on that too, i have a hard time thinking its as good as said...

http://cgi.ebay.com/ebaymotors/HD-T...m14&_trkparms=72:727|66:2|65:12|39:1|240:1318

 

[Chuckbear]

The ebay antenna is either the same or a knock off of the Boatenna which is still available and I believe for less money. I would go with the 2025 if you are on the fringe areas. we are receiving signals from Charleston which is 60 miles from us to the transmission tower. Others with the 2020 in our location do not pick up anything.

 

[Brian D]

Don't forget that TV is going digital on 2/17/09. May not affect all stations, but...

 

[kloudie1]

The digital signals seem to work better than the old vhf in my location on the North Shore, about 25-35 miles from the transmission towers in New Orleans. I am using a non-amplified set of “rabbit ears” inside the cabin. The digital signals are broadcast on the UHF frequencies, I think, so for your area, best to have an antenna that is specialized toward UHF and has an amplifier in it. Ya don’t have to have one that says “digital” on it, but because they will not have VHF capability, they will be able to be made smaller than most current boat antennae.. On the plus side, I suspect that the old antennae will be on sale soon as the transition to digital gets going.

 

[Chuckbear]

No difference between "old" and new antennas. The digital must be capable of picking up UHF signals, but not all VHF signals are going away so VHF is also needed. There is no difference in most antennas sold 10 years ago and those sold today that receive both UHF and VHF. Do not fall for sales pitches that sell "digital" antennas. There is no such thing. Almost all existing antennas will pick up the digital broadcasts but not all TVs will. You will need a converter box if you have an analog TV.

 

[ajsail1]

are digital signals infact stronger? reach wider area?

 

[Don S/V ILLusion]

Not stronger in the sense that more power is radiated by the transmitter but they are "stronger" in the context that dig signals are more compressed which has the advantage of using less bandwidth and compressing the power into a narrower spectrum making them easier to decode in a receiver's product detector. In some cases, the coverage area will effectively be reduced.

 

[Bill Roosa]

Digital band width

At best you can transmit 1 bit per cycle. In FM transmissions there is substantial bandwidth taken up because of the nature of the type of modulation, frequency in this case. Digital FM can reduce that bandwidth requirement because we are a)dealing with audio frequencies and b) only need 2 (more are used in practice) frequencies. So given a receiver that can distinguish between 1.000000 MHz and 1.000001 MHz you can transmit audio on a bandwidth of only 1 Hz at the MHz level. You can't do that in most cases because of noise. It does allow most FM stations and TV too to get more "bands" out of the amount of bandwidth the FCC has allocated to them. More bands equals more commercials and more $$$$$.

 

[Chuckbear]

Not speaking for radio but for TV there are NO digital antennas. The antenna needs to pick up UHF signals, period. If some one is selling a "digital antenna" for TV they are selling you a bill of goods.

 

[dvideohd]

There are a lot of perceptions - not quite "spot on".

An Analog band is typically considered to be 6MHz. In that, you have to squeezed a LOT of different elements - close caption, video (chroma and luma), audio of different types - and a LOT of dead space.

Digital resides in a similar space slot. It is considered to have 18MHz of usable bandwidth - kind of like an analog MODEMS that have 56K of data bandwidth in a 3K analog telephone bandwidth.

The wire antennas for an analog and digital antenna are the same alright... but there are some great differences as well.

Analog TV antennas - like rabbit ears - might have had a local active gain section (ie, need power) - but typically these were low gain - fairly noisy amps. Noisy amps WON'T work well for digital TV signals.

Digital TV antennas often have a MUCH MORE SOPHISTICATED active gain stage - so they need power. The gain stages are (a) much greater - up to 40+dB and (b) much lower noise - and flatter active gain regions. Lower Noise and Flatter Gain regions are CRITICAL to having a better TV signal. Digital TV antennas (like rabbit ears) are generally more precise.

Digital TVs are EXTREMELY PICKY about a quality signal. So an analog TV rabbit ears and a ditial TV rabbit ears - might have the same gains - but the old analot TV rabbit ears might not work. On marginal reception areas - you can really see this..

Digital TVs do not "fade gracefully" - the lock up the image - sound goes in and out - and generally are extremely annoying - as they get into marginal reception range. Orientation of the antenna is also more important for this. You don't the graceful fade of a SNOWY picture in Digital TV. Instead, the digital TV picuture will get PROFOUNDLY annoying - as the signal fades...

So the effective result is to get spottier reception - and also to get lower range quality reception with Digital TV. Not to mention that you need a good converter box - difference being how well it works with low level signals.

*************

In your antenna selection - you WANT a modern LOW NOISE, HIGH GAIN amplification stage.

good luck....

--jerry

BTW... like the man says...there does not have to be a difference between digital and analog antennas... so it CAN be a bill of goods. Having a more ACCURATE antenna, having a gain stage of 24 to48 dB, having a LOW NOISE local powered amp - these are clearly differences in the general world of Digital versus Analog antennas. Classically, the old analog antennas had gains stages of 3 to 12dB- and they were noisy - and they had a higher signal distortion. the older antennas worked ok for analog TV. Digital TVs require a higher quality - and level - signal.

 

[walt]

In Denver, the analog TV signals were located "all over the place" so you needed an antenna with directional gain all over the place or an antenna which could be pointed.

This last year, most of the stations went to a single location. I put up a Winegard "square shooter" at my house which is a very directional UHF antenna and it works very well.

I wonder if it will be more common in other cities to put all the station transmitters in a single location? Also interesting as someone else mentioned that while most of the digital transmitions will be UHF, there will still be some VHF channels (why, I dont know). I beleive the majority of the "digital" antenna's are optimized for UHF only.

 

[RobG]

dvideohd has it spot on, additionally...

There is one more difference between old analog and new "digital ready" antennas. It is called "front to back ratio". It is the antenna's ability to reject multi-path signals (the original signal reflected from different directions and timings from surrounding objects). Old antennas had in the range of a 3 to 1 ratio. Digital ready ones can run up to a 10 to 1 ratio, the higher the better. In this respect you pretty much get what you pay for and this certainly clouds the marketing.

There are a lot of perceptions - not quite "spot on".

An Analog band is typically considered to be 6MHz. In that, you have to squeezed a LOT of different elements - close caption, video (chroma and luma), audio of different types - and a LOT of dead space.

Digital resides in a similar space slot. It is considered to have 18MHz of usable bandwidth - kind of like an analog MODEMS that have 56K of data bandwidth in a 3K analog telephone bandwidth.

The wire antennas for an analog and digital antenna are the same alright... but there are some great differences as well.

Analog TV antennas - like rabbit ears - might have had a local active gain section (ie, need power) - but typically these were low gain - fairly noisy amps. Noisy amps WON'T work well for digital TV signals.

Digital TV antennas often have a MUCH MORE SOPHISTICATED active gain stage - so they need power. The gain stages are (a) much greater - up to 40+dB and (b) much lower noise - and flatter active gain regions. Lower Noise and Flatter Gain regions are CRITICAL to having a better TV signal. Digital TV antennas (like rabbit ears) are generally more precise.

Digital TVs are EXTREMELY PICKY about a quality signal. So an analog TV rabbit ears and a ditial TV rabbit ears - might have the same gains - but the old analot TV rabbit ears might not work. On marginal reception areas - you can really see this..

Digital TVs do not "fade gracefully" - the lock up the image - sound goes in and out - and generally are extremely annoying - as they get into marginal reception range. Orientation of the antenna is also more important for this. You don't the graceful fade of a SNOWY picture in Digital TV. Instead, the digital TV picuture will get PROFOUNDLY annoying - as the signal fades...

So the effective result is to get spottier reception - and also to get lower range quality reception with Digital TV. Not to mention that you need a good converter box - difference being how well it works with low level signals.

*************

In your antenna selection - you WANT a modern LOW NOISE, HIGH GAIN amplification stage.

good luck....

--jerry

BTW... like the man says...there does not have to be a difference between digital and analog antennas... so it CAN be a bill of goods. Having a more ACCURATE antenna, having a gain stage of 24 to48 dB, having a LOW NOISE local powered amp - these are clearly differences in the general world of Digital versus Analog antennas. Classically, the old analog antennas had gains stages of 3 to 12dB- and they were noisy - and they had a higher signal distortion. the older antennas worked ok for analog TV. Digital TVs require a higher quality - and level - signal.