Lowrance HDS-5

[Xino]

Re: Lowrance HDS-5

New broadband tech?

Broadband is adjustable frequency tuning. The HDS does not have this ability. Their reference to broadband is marketing at its best.........

Marketing eh? Useful info, thank you. HDS off my list now.

Cheers.

 

[jhebert]

Re: Lowrance HDS-5

There is confusion here about the term "broadband." I do not see anywhere that "broadband" is defined to mean that the SONAR frequency must be continuously variable or tunable.

The use of a tuned SONAR frequency is sometimes employed in commercial SONAR units so as to help detect particular species of fish. It appears that some species of fish are better detected by certain frequencies, so if you are a commercial trawler you might want to spend $20,000 for a unit whose frequency can be tuned for specific species.

However, I do not believe that LOWRANCE intends "broadband" to mean a tuned SONAR system like that, nor do any recreational fisherman interpret it that way.

LOWRANCE is not very specific in defining what they do mean by "broadband." I would interpret it to mean that the SONAR detector operates on a wide bandwidth, which tends to make the display of the echoes much sharper.

There is also the possibility that LOWRANCE is using a chirped SONAR technique to improve their sensitivity. This is a very sophisticated SONAR technique which produces much better sensitivity--which is one of the attributes claimed by LOWRANCE for its "broadband" products.

Thus I disagree with Mister Dingbat that LOWRANCE is not broadband--it is simply not what he has chosen to define for himself as broadband.

 

[dingbat]

Re: Lowrance HDS-5

There is confusion here about the term "broadband." I do not see anywhere that "broadband" is defined to mean that the SONAR frequency must be continuously variable or tunable.

Here is exactly I said,

Broadband is adjustable frequency tuning.

How you got "continuously variable or tunable" out of that sentence I don't know.

For the benefit of the people, please explain the difference between broadband sonar and narrow band sonar.

 

[jhebert]

Re: Lowrance HDS-5

We are going in circles. Because someone quotes an unidentified source--perhaps themselves--with a definition of "broadband," this does become the accepted meaning of "broadband."

There is no difference between the adjectives "adjustable" and "tunable" as applied to frequency that I can see. When a frequency is adjusted one often says it is tuned. Perhaps one can make an argument that there is a big difference between adjustable and tunable as applied to frequency. Feel free to explain it. In fifty years of radio use I haven't perceived a difference before.

I don't have a reliable source from LOWRANCE about what they mean by "broadband." One should not ask me for a definition of what LOWRANCE thinks the term "broadband" means--ask LOWRANCE.

To me, a broadband SONAR is one in which the bandwidth of the video detector is very high, and this increases the apparent resolution of the signal when it is raster-ized for display and viewing by the human operator. The visual perception is of a signal with more detail.

To me broadband has nothing whatsoever to do with the ability of the SONAR transmitter to be selectable to emit a pulse on more than one frequency. This feature has been in SONAR devices for years and is called "dual frequency." I cannot recall anyone ever confusing "dual-frequency" SONAR devices as being "broad-band" SONAR devices.

Another aspect of the signal which might be implied by "broadband" could be the nature of the emitted signal. Traditionally most SONAR devices emitted a pulse of energy which tended to be narrowly focused around a primary frequency. Modern SONAR techniques employ a brief but continuous wave output in which the frequency is modulated or ramped. This technique is commonly called a "chirped SONAR" and was not in common use in recreational SONAR devices due to the complexity and sophistication needed to detect and process the signal. However, with digital signal processor devices now very inexpensive, some modern recreational SONAR devices may be employing chirped SONAR. Again, I don't know if they do. Considering the general lack of electronic and mathematical sophistication that exists among most buyers of recreational SONAR devices, it would not surprise me to learn that a manufacturer might use a term like "broadband" instead of "chirped SONAR" to describe their product.

The term "broadband" has come into common use for many electronic devices, and it carries a generally favorable perception. To say one's SONAR is "broadband" is perhaps to ascribe to it a generally favorable impression. I believe this is the point of those who insist that "broadband" in SONAR is just marketing. However, I disagree. Broadband is a reasonable description of the enhancement, and it represent a true distinguishing characteristic.

In any case, I have a HDS SONAR and it gives terrific results.

 

[dingbat]

Re: Lowrance HDS-5

Another aspect of the signal which might be implied by "broadband" could be the nature of the emitted signal. Traditionally most SONAR devices emitted a pulse of energy which tended to be narrowly focused around a primary frequency. Modern SONAR techniques employ a brief but continuous wave output in which the frequency is modulated or ramped. This technique is commonly called a "chirped SONAR" and was not in common use in recreational SONAR devices due to the complexity and sophistication needed to detect and process the signal. However, with digital signal processor devices now very inexpensive, some modern recreational SONAR devices may be employing chirped SONAR. Again, I don't know if they do. Considering the general lack of electronic and mathematical sophistication that exists among most buyers of recreational SONAR devices, it would not surprise me to learn that a manufacturer might use a term like "broadband" instead of "chirped SONAR" to describe their product.

You may find it interesting that Simard's new BSM-2 is also named a Broadband Sounder. They go into great detail explaining the use of CHIRP technology in their "broadband" sounders. They go on ti state that CHIRP requires an "broadband" transducer and makes mention of Airmar BB transducers. You can use a conventional transducers but without the benefit of CHIRP. Given the fact that they are looking at a fairly wide spectrum of frequencies, I can see why you would need a good "broadband" transducer" to pull it off.

http://faq.airmar.com/index.php?action=artikel&cat=1&id=195&artlang=en

CHIRP signal processing overcomes these limitations Instead of using a pulse of a single carrier frequency, the frequency within the pulse is changed (swept) throughout the duration of transmission, from one frequency to another. For example, at the start of the transmission the sonar may operate at 300KHz, and at the end, it may have reached 350KHz - the difference between the starting and ending frequency is known as the 'Bandwidth' of the transmission, and typically the centre frequency of the transmission is used to identify the sonar (in this case it would be a 325KHz sonar).

http://www.tritech.co.uk/products/chirp.htm


So now we have two "Broadband Sounders". One with CHIRP and the other, who knows. Since they advertise you can use any transducer with the HDS, one can only surmise that they are using a very narrow frequency band, if at all, since true CHIRP requires a ?broadband? transducer.


If the HDS does indeed use CHIRP, why not offer a broadband transducer as an option?

 

[jhebert]

Re: Lowrance HDS-5

I was hoping your links pointed to information from SIMRAD about their new SONAR describing it in more detail. :-(

 

[dingbat]

Re: Lowrance HDS-5

http://www.simrad-yachting.com/Products/Navigation-Fishfinding/Simrad-BSM-2/

 

[jhebert]

Re: Lowrance HDS-5

Thanks for the excellent link to the SIMRAD website about their new chirped SONAR. On there they say:

"The first such fishfinder to demonstrate the benefits of CHIRP, the Simrad BSM-2 utilises both new broadband and existing narrowband transducers to their fullest potential...."

I guess if the BSM-2 is the first fishfinder to use chirped SONAR, one could conclude that the current HDS Lowrance devices do not use chirped SONAR. This is not particularly surprising, as among the product lines of NAVICO, the SIMRAD brand is positioned as the more advanced and more expensive option. SIMRAD says:

"The Simrad BSM-2 is the perfect unit for dedicated offshore sports fisherman and professional boats looking to give their clients the best possible experience."

In the context of the low-cost HDS-5 and where it might be used, I suspect this BSM-2 and associated multi-function display device would cost more than some of the boats you'd see using an HDS-5.

 

[semperfifishing]

Re: Lowrance HDS-5

"There is confusion here about the term "broadband." I do not see anywhere that "broadband" is defined to mean that the SONAR frequency must be continuously variable or tunable.


LOWRANCE is not very specific in defining what they do mean by "broadband." I would interpret it to mean that the SONAR detector operates on a wide bandwidth, which tends to make the display of the echoes much sharper."
......................................................................................................

Lowrance is not very specific indeed.
Currently Airmar is the leader in Broadband transducers and the BSM-2 (SIMRAD) is the only sonar now in the current recreational market that is capable of using the full potential of the broadband transducers.

Lowrance it seems is only interested in using the potential of the broadband name..to tag along on the shirttails and get a free ride.

http://www.airmartechnology.com/uploads/news/June airmar sounder.pdf

The HDS does not incorporate CHIRP nor is it even close. The HDS uses the same standard analog circuit it has for many years but has added digital filtering and an enhanced graphic card to give vitality and punch to its display.
But all in all what one has now is simply a hybrid unit that is part video game and part sonar.

 

[steveausten555]

Re: Lowrance HDS-5

Thanks all of you for the info....

Lowrance Hds-5

 

[SmokinBarrel]

Re: Lowrance HDS-5

Why can't Airmar make a transducer with a wide beam with two or three elements?

83/200 with 60 degrees, or something along those lines? I guess they want to focus on offshore versus inshore? It seems most of their transducers are geared towards deeper water.

 

[dingbat]

Re: Lowrance HDS-5

Why can't Airmar make a transducer with a wide beam with two or three elements?

83/200 with 60 degrees, or something along those lines? I guess they want to focus on offshore versus inshore? It seems most of their transducers are geared towards deeper water.

Follow the money. How many "lake" fisherman are going to buy an $800 transducer and the $2,500 head unit power it?

 

[jhebert]

Re: Lowrance HDS-5

If you compare almost any two products where one of them costs ten-times more than the other, the outcome is normally in favor of the more expensive one. Why would anyone think that a $500 Lowrance HDS-5 will perform as well as a $5,000 state-of-the-art SIMRAD BSM-2 SONAR? For goodness sake, they're both made by the same conglomerate, NAVICO. Why would NAVICO offer the same components and performance for $500 in a Lowrance that they can sell for ten times as much in a SIMRAD?