One area in which automotive electronics is changing rapidly is the automotive audio system. Along with the outwardly visible trends, such as the progression to radio/cassette/CD systems, there are internal technical changes. Among these is the transition from analog to digital signal processor-based audio signal processing.
DSPs have already begun to show up in the in-dash radio/cassette/CD systems, handling signal processing tasks such as user equalization, sound-field effects processing and noise reduction for the cassette player. A less obvious emerging application for DSP-based audio-signal processing is in the front end of the automotive audio power amplifier.
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The audio system in a typical mid- to high-end vehicle consists of an in-dash radio, or "head unit," and a separate audio power amplifier. The head unit typically includes an AM/FM tuner and a cassette tape player and/or CD player. The head unit's user interface provides the means to select the audio source, along with controls for adjusting the audio signal volume, pan (left/right balance), front/rear fader (front/rear balance) and equalization (generally a bass and treble control, or a graphic equalizer).
he left-channel output feeds both front- and rear-channel amplifiers, as does the right-channel output. Thus, there are four analog outputs, even though the audio sources are only stereophonic (two channels). The front and rear channels generally carry the same stereo program, but at different signal levels as dictated by the front/rear fader control. The volume and pan controls also affect the signal levels on the four analog outputs.
(https://i.imgur.com/ssMpuQQ.jpg)
The four analog outputs from the head unit are routed to the audio amplifier, which drives the loudspeakers located in the front and rear of the vehicle. In addition to power amplification, the audio amplifier generally includes some vehicle model-specific filtering or equalization. This equalization is used to compensate for vehicle-specific spectral characteristics, such as the type of speakers used, the location of the speakers and the spectral response of the passenger cabin itself. Inclusion of any vehicle-specific signal processing in the amplifier is advantageous because it isolates the head unit from the model-specific sound delivery system.
However, there is a major drawback. The amplifier must be calibrated, or tuned, to each vehicle model in which the design is to be used. Tuning is often accomplished by iteratively running spectral measurements and listening tests while changing the resistors and capacitors in the filter circuits on the amplifier circuit board. This procedure is time-consuming. And, the manufacturer must stock a separate amplifier for each vehicle model. Amplifiers are often built using the same circuit board with different bills of materials. https://medium.com/@carspeakerland/what-are-the-speaker-sizes-in-my-car-speaker-size-for-my-car-c32cccff8dbb (https://medium.com/@carspeakerland/what-are-the-speaker-sizes-in-my-car-speaker-size-for-my-car-c32cccff8dbb)
The four-channel amplifier can be used to drive four full-range speakers. Alternatively, passive crossover filters may be used to separate the low and high frequencies to drive a two-way speaker configuration. Another approach is to employ an active crossover in the amplifier, and drive the low- and high-frequency transducers-the woofer and tweeter-with separate power amplifiers.
This approach can directly deliver all of the amplifier power to the transducers, where the passive-crossover approach will dissipate some of the amplifier output power in the passive-crossover components.
Digital signal processing can be used in place of analog circuitry for such functions as equalization and active-crossover filtering. In addition, DSP allows for the practical implementation of a number of features that would be impractical using analog circuitry - for example, adaptive signal-level-limiting functions or multichannel time delay for speaker alignment.
(https://i.imgur.com/VwirRqw.jpg)
However, the strongest factors motivating the auto-amplifier industry to transition from analog to digital signal processing are related to manufacturability, rather than to new features or cost savings. The attractiveness of DSP implementation can be attributed to the ease of reconfiguring the amplifier without changing components.
For the amplifier maker, this can dramatically speed the tuning process, saving time and enabling the supplier to be more responsive to the customer: the automobile manufacturer. Reconfigurability of the DSP-based amplifier also allows the same amplifier to be used in different vehicle models, simplifying the automobile maker's inventory management.
The amplifier can then be programmed for the particular vehicle model at installation, or configuration can even be accomplished automatically if the amplifier has an interface to one of the in-vehicle control buses-commonly, the J1850 bus for U.S. manufacturers or the CAN bus for European vehicles.
The components for a six-channel DSP-based amplifier include four analog-to-digital (A/D) conversion channels that convert the analog input signals into digital format, a DSP engine, typically 24-bit fixed-point for audio processing, with the associated program and data memories, and six channels of digital-to-analog (D/A) conversion.
This system also includes an interface to a serial control bus. The bus can be used to interactively reconfigure the amplifier's signal-processing functions during the vehicle model-specific tuning process. After the design has been tuned, the settings for a number of different vehicle models can be stored in the amplifier's internal memory, allowing the same amplifier to be easily reconfigured for any of the target vehicles.
The configuration may be done manually prior to installation in the vehicle or, if the amplifier is connected to an in-vehicle control bus, done automatically within the vehicle.
The graphical user interface (GUI) of the Crystal Semiconductor CF4912CAR-01 firmware kit simplifies the DSP-based amplifier tuning process. Basically, the DSP code runs on the CRD4912 board and the GUI application runs on a personal computer under the Microsoft Windows 95 operating system. The process of tuning the CRD4912 board's DSP algorithms using the PC-based GUI is analogous to the amplifier tuning process described.
The software provides a graphical depiction of the signal flow through the signal-processing functions. Clicking with the mouse on any of the signal-processing blocks will bring up a more-detailed screen, which is used to configure the characteristics of that processing function. This reduces the tuning process from weeks to days.
One of the difficulties in DSP-based systems is maintaining good dynamic range. The problem is that the user volume, pan and fader controls scale the signal level in the head unit. This means that the signal level going into the amplifier may be tens of decibels below optimal for typical listening conditions. Operating in this scenario requires very good dynamic range in the amplifier's A/Ds and D/As.
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A solution would be to convey the current user settings for volume, pan and fader from the head unit to the amplifier over a control-bus connection between the two units. The head unit could then be designed to output a full-scale signal level, regardless of the user settings. Once the fader is implemented in the amplifier, the audio signal path between the head unit and the amplifier is reduced from four channels to stereo.
It's always a good idea to have extra fluids for the car (oil, engine coolant) handy.
A car.
I need to start bringing bubble gum to treat motion sickness.
Quote from: bandit957 on September 22, 2017, 05:41:34 PM
I need to start bringing bubble gum to treat motion sickness.
Only if it's pre-chewed, though.
Quote from: tribar on September 22, 2017, 04:51:13 PM
A car.
Cash and/or credit card would also fit that category.
Food, water, phone, money for gas.
On am ore serious note, here's an earlier thread on the topic:
https://www.aaroads.com/forum/index.php?topic=16599.0
I've always been a proponent of bringing more music than the travel time would suggest is necessary so that there are options if you get tired of something or aren't in the mood for something.
Are you a passenger, rather than the driver? From the nature of your post, I assume that's the case.
If I'm along for the ride, I tend to bring external batteries for my devices to keep them charged if a charging port is unavailable in the car. I'll also bring drinks and snacks in case I get hungry or thirsty in between stops.
Quote from: CNGL-Leudimin on September 24, 2017, 04:59:41 PM
Quote from: Brandon on September 22, 2017, 05:28:25 PM
Quote from: tribar on September 22, 2017, 04:51:13 PM
A car.
Well, no shit, Sherlock.
Not necessarily. I now do my road trips with a van :sombrero:.
Back in July 2008, we encountered two guys in Nova Scotia who were roadtripping from Victoria to St. John's on recumbent trikes.
Quote from: 1995hoo on September 24, 2017, 12:57:22 PM
I've always been a proponent of bringing more music than the travel time would suggest is necessary so that there are options if you get tired of something or aren't in the mood for something.
Radio used to be sufficient, but nobody wants to listen to the garbage that fills the airwaves nowadays.
A pillow or blanket is nice for the passengers sleep with, depending how long you intend on driving each day.
My suggestions:
Thermoelectric Cooler (http://amzn.to/2y5Li43)
USB Car Charger (http://amzn.to/2xDPC9g) and extra USB cables
El Cheapo Bluetooth Headsets (http://amzn.to/2xDyZdH)
Sanitizing Hand Wipes (http://amzn.to/2k0s2Pa)
WalMart and Smart&Final are great for cheap drinks.
Quote from: ZLoth on September 26, 2017, 03:07:02 PM
My suggestions:
Thermoelectric Cooler (http://amzn.to/2y5Li43)
Could also get an AC adapter, so you can use the cooler in a motel or other place outside your car. Both coolers and adapters can be found at Pilot or other travel centers/truck stops.
Thermoelectric coolers can also be turned into heaters, by reversing the plug, in case you need to keep food warm. Just be sure to plug it in the right way. Unpleasant when your soda cans overheat and explode in your car or motel room.
Water bottle, two if going through the desert.
Map
Quote from: bandit957 on September 26, 2017, 11:12:11 AM
Quote from: 1995hoo on September 24, 2017, 12:57:22 PM
I've always been a proponent of bringing more music than the travel time would suggest is necessary so that there are options if you get tired of something or aren't in the mood for something.
Radio used to be sufficient, but nobody wants to listen to the garbage that fills the airwaves nowadays.
I've never found radio sufficient, other than satellite radio, for the simple reason that I dislike hunting for stations I'd like when I'm in an unfamiliar area.
Quote from: 1995hoo on September 26, 2017, 09:14:53 PM\
I've never found radio sufficient, other than satellite radio, for the simple reason that I dislike hunting for stations I'd like when I'm in an unfamiliar area.
That used to be part of the fun! There used to be books that listed all the stations.
Stations were actually different back then based on region or market size.
Money to pay for the speeding tickets from trying to get from Texas to North Carolina in 8 hours.
Quote from: NE2 on September 27, 2017, 10:08:05 AM
Money to pay for the speeding tickets from trying to get from Texas to North Carolina in 8 hours.
Mabye they will ignore the police cars.
Quote from: Roadgeekteen on September 27, 2017, 05:02:49 PM
Quote from: NE2 on September 27, 2017, 10:08:05 AM
Money to pay for the speeding tickets from trying to get from Texas to North Carolina in 8 hours.
Mabye they will ignore the police cars.
Driving away from a police car when it's trying to pull you over results in much more serious consequences than stopping when you're supposed to.
Quote from: 1 on September 27, 2017, 05:16:49 PM
Quote from: Roadgeekteen on September 27, 2017, 05:02:49 PM
Quote from: NE2 on September 27, 2017, 10:08:05 AM
Money to pay for the speeding tickets from trying to get from Texas to North Carolina in 8 hours.
Mabye they will ignore the police cars.
Driving away from a police car when it's trying to pull you over results in much more serious consequences than stopping when you're supposed to.
Well then, 8 hour police chase across state lines. I would watch a tv show of this happening.
Quote from: Roadgeekteen on September 27, 2017, 05:18:14 PM
Quote from: 1 on September 27, 2017, 05:16:49 PM
Quote from: Roadgeekteen on September 27, 2017, 05:02:49 PM
Quote from: NE2 on September 27, 2017, 10:08:05 AM
Money to pay for the speeding tickets from trying to get from Texas to North Carolina in 8 hours.
Mabye they will ignore the police cars.
Driving away from a police car when it's trying to pull you over results in much more serious consequences than stopping when you're supposed to.
Well then, 8 hour police chase across state lines. I would watch a tv show of this happening.
Smokey and the Bandit!
Z981
Quote from: Roadgeekteen on September 27, 2017, 05:18:14 PM
Quote from: 1 on September 27, 2017, 05:16:49 PM
Quote from: Roadgeekteen on September 27, 2017, 05:02:49 PM
Quote from: NE2 on September 27, 2017, 10:08:05 AM
Money to pay for the speeding tickets from trying to get from Texas to North Carolina in 8 hours.
Mabye they will ignore the police cars.
Driving away from a police car when it's trying to pull you over results in much more serious consequences than stopping when you're supposed to.
Well then, 8 hour police chase across state lines. I would watch a tv show of this happening.
I might, but only if they edited it down to the interesting 20 minutes.
Quote from: kkt on September 27, 2017, 05:57:12 PM
Quote from: Roadgeekteen on September 27, 2017, 05:18:14 PM
Quote from: 1 on September 27, 2017, 05:16:49 PM
Quote from: Roadgeekteen on September 27, 2017, 05:02:49 PM
Quote from: NE2 on September 27, 2017, 10:08:05 AM
Money to pay for the speeding tickets from trying to get from Texas to North Carolina in 8 hours.
Mabye they will ignore the police cars.
Driving away from a police car when it's trying to pull you over results in much more serious consequences than stopping when you're supposed to.
Well then, 8 hour police chase across state lines. I would watch a tv show of this happening.
I might, but only if they edited it down to the interesting 20 minutes.
Are police cars allowed to chase across state borders?
Answering the question originally posted: I bring bottled water (reusing disposable water bottles), money (both cash and a credit card that is used for the float only), and a smartphone with an up-to-date data plan from a service provider with good 4G availability.
Everything else depends on the nature and scope of the trip. If it passes through states that have a land border with another country, I take my passport even if I don't intend to cross the border. If it is a longish sightseeing trip, I take AAA TourBooks and paper maps (yes, even though I have a smartphone--Google Maps' mobile interface does not allow you to modify routes by dragging and dropping). If I expect to encounter expensive lodging or my time on the road overlaps a holiday weekend, I take camping equipment (tent, air mattress, sleeping bag, and two pillows). In addition to the smartphone, I take along a point-and-shoot digital camera that uses AA batteries, and for trips longer than two or three days I also take a Ni-MH battery charger.
Reading upthread here and also in the earlier thread linked to above, I see many recommendations to carry tools and supplies for the car, such as air compressors, jumper cables, socket sets, oil, coolant, etc. With the possible exceptions of jumper cables and trips to remote areas such as northern Alaska, I respectfully disagree. I used to carry an elaborate kit in the trunk that included a socket set, wrenches, funnels, rubber hose and a basting syringe (to start siphons), one quart each of motor oil and Dexron III/Mercon automatic transmission fluid, a redwood plank, jumper cables, air compressor, and an emergency blanket. Only the socket set and air compressor saw regular use; I don't do oil changes on the road anymore, and I now prefer to use a different air compressor that runs off wall current. Getting rid of the now-obsolete motor oil and ATF has become a minor headache. The very few times I actually used the jumper cables, they were invariably to give someone else a jump, and about half the time his or her car wouldn't start anyway.
For trips that take advantage of well-developed road infrastructure (e.g., not along the Dempster Highway), I'd contend money, time, and effort is better invested evaluating the general roadworthiness of the car so that any potentially disabling problems are identified and, if possible, fixed before departure, and supplies that are taken are closely tailored to actual need. E.g., for the 2005 Toyota Camry V6, I never carry oil because I know with certainty that it burns no oil, but for the 1994 Saturn SL2, I would carry at least a starter quart because careful prior measurement has established that it burns oil at a rate of 1500 MPQ (up to 1000 MPQ at highway speeds), and I would also be prepared to stop at Walmart as needed to buy additional oil.
In general I am not a fan of anything that runs off the car battery through the cigarette lighter socket, whether the engine is running or not. Over time, discharge while the engine is not running kills the starting batteries that are typically original equipment in most cars, and while deep-discharge batteries are available for automotive applications (e.g., Optima Yellow Top), carrying additional running loads and/or backfilling discharge from accessory usage also shortens the life of the alternator. I do carry a lighter socket plug for the smartphone but it is for emergency use only. I don't use plug-in coolers, reversible or not; the food I buy on the road tends either to keep for a while in the trunk (e.g., carrots, apples) or to be eaten immediately after purchase (e.g., Caesar or southwestern salads from Walmart--usually slightly less than $4 for about 700 calories--when it is late or TripAdvisor study of sit-down restaurant options turns up nothing promising).
I try to keep the passenger cabin picked up (no cargo visible except water bottles and coffee cups) since this helps offset the risk of being Z'ed by thieves for having out-of-state license plates.
Quote from: Adrienne224 on September 12, 2017, 04:48:48 AM
My family is going on a road trip to north carolina which is 8 hours from where i live. What should i bring for in the car and when I'm there? :love:
Your curiosity. However, the OP posted this over 2 weeks ago, and hasn't logged in since a week ago (shortly after the post drew its first response), so I'd say that's lacking.
Quote from: J N Winkler on September 27, 2017, 09:10:04 PM
a smartphone with an up-to-date data plan from a service provider with good 4G availability.
Actually, if you plan ahead, you can download the Google Maps to your phone (http://markholtz.info/googleofflinemaps) so that you can save your data plan. I found this handy during a recent flight and cruise. Also, there is poor-to-no cell coverage in Death Valley (http://markholtz.info/1pa).
Quote from: jwolfer on September 27, 2017, 05:25:35 PM
Quote from: Roadgeekteen on September 27, 2017, 05:18:14 PM
Quote from: 1 on September 27, 2017, 05:16:49 PM
Quote from: Roadgeekteen on September 27, 2017, 05:02:49 PM
Quote from: NE2 on September 27, 2017, 10:08:05 AM
Money to pay for the speeding tickets from trying to get from Texas to North Carolina in 8 hours.
Mabye they will ignore the police cars.
Driving away from a police car when it's trying to pull you over results in much more serious consequences than stopping when you're supposed to.
Well then, 8 hour police chase across state lines. I would watch a tv show of this happening.
Smokey and the Bandit!
Z981
Nah. The Chase - Sheen and Swanson